I bought one of the first 5D2s available... In a studio setting, with a 135 L on it, the results were just plain stellar! And landscapes with the nikon 14-24 -- wow!
Now, when it comes to actually using the autofocus, well, I have never been so frustrated! This comes from a Canon "fanboy" who had a long time love affair with the 5D. I enjoy taking street and candids and, the 5d2 proved to be a less than great tool in these conditions.
Another issue that seemed minor when I purchased the camera but slowly grew unbearable, was the shutter delay/mirror black out. The gold standard was my M8, with its immediate response and no black out. The opposite being a digital point and shoot, with the long pause between shutter release and actual picture. The 5D2 seemed almost like the latter, with a click, pause, wait, picture that almost ensured that I missed that perfect moment I was trying to capture. Again, not an issue in the studio or landscape setting, but just the devil when trying to capture candids. And, focusing manually my alt glass was painful, like pulling out my own fingernails. Even with a focusing screen.
So, in the end, I got suckered into the megapixel race, the size matters mentality. Look how big the sensor is!!! 21 MP. Everything else is just not enough!!! I mean, who doesn't want to be able to print a billboard? I print that size all the time! Don't I? OK, I never do. I was so frustrated that I actually thought of throwing all this expensive gear into the trash. I mean, all I wanted was a great sensor, like the one the 5D had, with a better build, more solid body, some weather sealing, more FPS, more reponsive/less shutter lag. Maybe even with some sort of focus-aide for manual lenses, like a built in rangefinder focus or something. You know, kind of a 5D with a 1-series build. The mythical Canon 3D, or what the 5D2 could have been. Canon, where is it?
Then I went to the camera store and someone handed me a D700... Oh, that's what happened to the 3D! Now, I am happy again. My manual focus lenses focus fast AND accurately? What?!? No way? And the autofocus, wowow. And the build and the... well I could go on. Suffice it to say, for an amateur who doesn't want the size of the 1-series or D3 series body, the D700 is like driving a 5 series BMW or a Audi A6, not the most expensive or fastest in the line up, but very upscale, well built, responsive, and when do I need to go 150 miles an hour (or print much bigger than A3+)?
Don't get me wrong, for landscapes, the 5D2 seems like a dream. But for me, as someone who shoots portraits and landscapes AND street AND candids AND fashion... My long awaited 5D2 just, well, just left me defeated. And I soooo wanted to love it! I am a bit surprised that Canon put such a mediocre focusing system in a camera with stellar low light potential. I mean, how do you shoot low light candids when the cam takes forever to find focus? The specs of the A900 make more sense -- the A900 with its huge dynamic range, ISO good to 800 makes much more sense as a landscape/studio choice, as light is controlled and you want to shoot at low ISO anyway.
OK, I'm rambling now. Bottom line, I wish I had not gotten so caught up in all the camera hype. Once you commit to a cam, it is hard to say anything negative about that purchase because you have yourself invested in it. And, admitting you made a poor decision also means people might think that you are not a smart person... Oh well. (I'm also one of those people who loves the M8, but most of the cam world makes fun of the M8 and its "shortcomings," so...)--Rob