• In case you were wondering, the old 5D batteries will not work in the Mark II… the batteries might look similar, but the contacts are in different positions. Mark II batteries are very hard to come by right now and I don't feel overly comfortable working without a backup. I like to have at least two batteries (usually three) and two or three chargers. I leave one in my bus, back one in my camera bag and leave one in my car which I can use with an inverter.
• I really wish Canon would add an auto focus assist lamp to their cameras. In low light it can be more difficult to get good focus. This is nothing new… I'm just amazed the engineers at canon don't shoot in low light without a flash.
• I think it's really dumb that they list the expanded ISO in real numbers. Instead of seeing ISO 25600, I see H2. Also, anything over ISO 3200 is not all that usable (too noisy), but I always have ISO expansion turned on simply so I can have access to ISO 50 when I need to use longer exposures when shooting waterfalls. Just wish it would show up as 50 instead of "L". 
• There is now an auto ISO setting which will automatically set the ISO for between 100-3200 which can be nice when shooting in low light and few brain cells functioning. I don't leave this mode turned on all the time because it will automatically set the ISO to 400 when using Manual, Bulb or Flash. 
• I love the idea of the new sRAW format which allows you to shoot at lower resolutions in the raw format (like 10 or 5 megapixels). I hope to use this for files that I pass around in classrooms so that I don't have to use so much space or give away my high resolution ready for publication images.  
• I really wish Canon would have included an electronic level indicator like some Nikon camera's feature. Who wants to carry an easily loose-able bubble level in their camera bag? 
• I wish they would have redesigned the eyepiece and diopter adjustment wheel. They are pretty much the same as on the original 5D where I quickly lost the eyepiece rubber surround (even the replacement one I bought) and often found the diopter got chanced when moving the camera in or out of my camera bag. 
• I live that there is now a two second self timer setting which is very useful when you forgot to bring a cable release and need to make a long exposure.  
• I like that they moved the top LCD backlight button. I always had trouble finding it in the old 5D and the new position right behind the shutter butter makes it overly easy to access.  
• There is a new Info screen on the back LCD display that will mirror all the settings that are shown on the top LCD. I absolutely love this feature since I often have the camera on a tall tripod where it's almost impossible to see the top LCD without tilting the camera. It's also helpful that text is included along with icons to make it easier to figure out which icon will give you spot metering versus center weighted metering, etc.  
• I have the new Really Right Stuff L-bracket that I use for attaching the camera to my tripod. I find the new version to be smoother in shape, smaller in two dimensions and it seems to have a slightly more solid connection where it's more difficult to twist the camera within the bracket.
• They have added an additional button where your thumb would rest on the back of the camera that can be used to trigger the auto focus. I like this because unlike the original 5D, you do not need to give up your EAlock button if you want a separate button for triggering auto focusing. It's also more comfortable than the button used on the 5D. 
• There is now an ambient light sensor right below the rear LCD screen which automatically adjusts the brightness of the screen. I like that because it keeps the screen darkish when shooting at night which helps to prevent loss of your night vision.
• There are now three user settings on the mode dial on the top of the camera compared to the original 5D's single custom user mode. I find that to be very useful since I can now setup one with auto bracketing for HDR shots, one for panoramas, one for night shooting with auto-ISO, etc.  
• The hot shoe on top of the camera looks a little different and makes a much more positive seal when using the new 580EX II flash. It looks to actually be a bit weather tight. 
• The camera now has a microphone and speaker, but they can only be used when recording movies. I really wish I could use them to add meta data to images much you can on higher end Canon 1-series cameras. That way I could easily capture a model's name without having to write something down. 
• The camera how has a sensor cleaning system which I have not had time to test (I've only had the camera for less than 24 hours). I am just a bit surprised that your options for using it are to either manually trigger it or have it automatically applied every time the camera is powered on or off. I'd like it to be automatically done each time I change lenses since that's when the majority of dust makes it onto the sensor of the camera.  
• I haven't tested the movie capture capability yet. But in reading the manual, I did learn one thing that will prevent the 5D mark II from completely replacing a normal video camera: There is auto focus, but it does not have continuous auto focus. You have to press a button and then the camera takes up to three seconds to find focus. That means that it will be difficult to shoot transitions between scenes where the main subject is at a different position in each scene. I guess I'll have to get used to doing manual focus tracking.  
• In case you were wondering… you *can* shoot full resolution photos while you're in the middle of recording video. The video will display a still frame for about one second as the camera captures a high res image and then will immediately return to recording video.  
• I like the new Live View since it will allow me to preview depth of field without having the image go dark and I can zoom in to 10x to check and adjust focus.  
• You can now trigger the shutter using an optional Infrared remote because they've added a new sensor on the front of the camera body. Also, when in bulb mode you can press once on the remote to open the shutter and then press a second time to finish the exposure which should help in my light painting adventures. 
• The new menu system is a joy to use compared to the single list that was found on the original 5D. I like that I can setup a separate menu and choose which settings I'd like to have appear. That way I can include up to six of my most used menu functions at easy reach. I couldn't stand having to cycle through the entire menu on the old camera just to find the 3-4 settings that I used on a regular basis.  
• I don't mind that the Jump button is gone from the back of the camera since I can always use the control dial near the shutter button to jump forward or back when viewing images in thumbnail mode.  
• There is a new picture style button on the back of the camera which I doubt I'll ever use. I think it only applies to JPG images or RAW files that are opened in Canon's software. I use Camera Raw and Photoshop or Lightroom which I'm almost sure will ignore the settings. So, why not let me assign something else to that button? It reminds me of the old print button that was to the left of the viewfinder on the 5D… a button I never pressed. Although on the Mark II that button now brings up live view mode where you can either record movies or see the view of your scene on the rear LCD screen.  
• The larger LCD screen on the back is a nice improvement. Now I just have to get a Hoodman lupe for a 3" screen so I can get a really good view of the image in broad daylight.  
• You can now get the highlight warning (also known as the blinkies) on a full size image. In the old camera, the blinkies would only show up when you were viewing a histogram and that made the image so small that the blinkies were hard to see. This new setup is a great improvement from the old since you can have blinkies visible regardless of which view you choose to review your images in. 
• Being an HDR shooter, I still wish the camera's exposure compensation could go to -3 and +3 like the 1 series cameras (it's still limited to -2 and +2) and I wish the auto bracketing could shoot more than the default three shots. Nothing new there.  
• You can now see your battery capacity in 1% increments if you use the rear LCD screen. You can also see the battery level of up to six batteries. That means you can tell if the five other batteries in your camera bag are charged or not (assuming you haven't been using up their power in a different camera). 
• I really like that I can control the settings on my 580EXII Speedlite from the LCD on the back of the 5D Mark II. This is especially useful when trying to set a custom function since the LCD will include text clues as to which function does what on the flash instead of just being presented with a numbered list and numbered settings with no text like what you'd get on the flash itself. I can see that it's possible to control the flash level of up to three groups of off camera flashes, but I haven't figured out how to get that to really work yet. 
• Adobe seems to have timed their software updates just right since I was able to download an update to both Lightroom and Adobe Camera Raw that claims to support the Mark II. I haven't had a chance to test things yet, but it should work in theory. 

Well, that's all that comes to mind at the moment. I haven't done any serious shooting with the camera yet, so I'm sure I'll have more to report later. I also haven't had a chance to test for the black dot issue (Dark dots appearing on the edge of blown out highlights) that some people have reported on the internet. It sounds like Canon might release a firmware update in January to deal with the issue. Overall, I'm very happy with what Canon as done with the Mark II.