Does anyone consider the '08 Corvette a "vast" improvement? What I mean, was there really that much to improve, and are the things that've been changed for '08 major, or just minor fixes normal to the life of any car model?  

Vastly improved?  Not really.  The jump from the LS2 to the LS3 for the base model is really nice, however, most of the differences seem to be primarily cosmetic.  But that's to be expected during a model run.  The vast improvements will be when we migrate to the C7, anything up until then will be fairly minor, outside of engine upgrades.