The 5D Mark II is still an excellent camera. I, along with thousands of other photographers, still shoot with it daily. I bought mine last winter, knowing it was at the end of the product cycle, when the price with the 24-105 came down below $2800. I'd never owned a full frame digital camera, instead using 40D bodies for personal work and 1D Mark IV bodies for actual work.
The 5D2 is significantly better than the 40D in pretty much every possible way, with the minor exception of shooting speed. Autofocus is decent, not the same as the 1D series cameras, but I'm getting very good results. Better than I expected, to be honest. The files are lovely, even at high ISO speeds. The 24-105 is an excellent lens, and joins my 70-200/4 for personal work and days when I want to carry lighter gear.
Now I use the 5D2 in general rotation at work, mixed in with the 1D bodies. The larger sensor gives me a different look than the 1.3x APS-H sensors in the 1D4's, and the files are comparable in quality. I use it for portraits, architecture and landscapes, and general photojournalism. Not sports, though.
If I needed another camera, I'd almost certainly buy another 5D Mark II. While the Mark III is newer and "better," for me it wouldn't justify the extra $1500 over the Mark II right now. I really didn't expect to like this camera as much as I do.
EDIT: If you own EF-S lenses, that might be a reason to look at the 7D. However, having tested a 7D when it came out, I'm much happier with the files from the 5D2