For the price imo the 5D is severely underrated
Check out Ken Rockwell's review of the 5D, he absolutely loves it even though he is a Nikon fanboy. At the time of his review the 5D was still worth $1800 used, and he said it's the best camera under $8000.
As of right now, you have people jumping all over the 7D, as well as other cameras because of all the newer features- live view, movie modes, etc. The 5DmkII is great but I can't afford it, and the 7D is not enough of an upgrade (IQ wise) from a 40D, and I don't need to shoot at 8fps or have the super tough build quality.
I was hesitant to buy a 5D because of the lack of newer features (I think this would be the case with most people who are afraid to buy one), in fact it took me a year to finally decide to buy one. I wasted lots of time researching lenses (Tamron 17-50VC, Sigma 17-50OS, Canon 17-50IS) but in the end the shallow DOF and incredible detail from a FF sensor makes all the difference. My $220 Sigma 24-60 f/2.8 I bought off Amazon looks better then either of those three lenses now (on FF, not necessarily crop) it's got a whole new personality! Either I have a super good copy, or I will be incredibly amazed at my camera if I pop an L zoom on it!