The way people on various photo forums across the globe talk, you would think that your old camera will stop working the moment a new one is announced. NOT SO! Don't throw out that crappy 5D because the ISO noise at ISO800 is like sand on a volcanic beach, no really, it will still work the way it did before the 5DmkII was announced.
As for my 5DmkII, yes, it still works even though the 5DmkIII was announced. Isn't that amazing! I had communicated with my friend Bill in Florida, he has a whole load of gear. It is just not so much fun any more, he told me, it is all about the new best feature in the new best camera which makes your old one defunct. Bill gets out more with light gear now, not a bad idea (at his age ;) )
So I read the "feature list" of the 5DmkIII and basically the most innovative thing is the scroll wheel, which becomes touch sensitive for video shooting so there are no vibrations. Great idea but why not implement it for all uses of the scroll wheel, get rid of the wheel, remove a moving part! Of course the AF module is superfandribbletastic but it should have been built into the 5DmkII years ago.
Maybe you can tell that I don't buy into the latest and greatest. I know the price, ridiculous as it is, will drop over the coming months. Cameras never hold value, but glass does. I await that thousands of people across the globe test the camera before I buy it (remember the 1DmkIII??) and get Canon to refine it a little with firmware (yeh I know, 1DmkIII). Eventually I may buy one, when my mkII battery only lasts for 100 shots or the noise is so bad I cannot possible shoot at ISO800. Yes I would love to shoot at ISO3200 but convincing me that it is possible with a Canon is up to the public, and some decent samples.
For now I do my best to get out with my 7D (which I love and hate very much) and my 5DmkII...both still work, both still take pictures neither cost me the same as a used 300 2.8 IS, no not even together!!
Here is the proof. Yes, I got out for once. Sat patiently for three hours under a hardwood realtree type throw over hide. It worked a treat, the deer were far more concerned with the cyclists passing 300m away than they were of me. Cool!