I rented the 24-70ii two weeks ago to see what the deal was. My thoughts are if you are in the market for, or looking to replace, any two of the following three lenses: 24L, 35L, 50L, with the added convenience of a zoom then it's price is not too steep and probably right on. Essentially my feeling is this is a prime replacement zoom if you truly don't need the extra stops of light in a prime, but still want stellar IQ. You don't give up any sharpness, in fact I suspect you gain some. For just about anyone else either the mark I, or the be quite honest, the new Tamron 24-70, are probably more than adequate. I'm still on the fence as to whether I will order the new Canon simply because the Tammy does a good enough job and is far sharper than any 24-70i I ever used. The VC is a added bonus that does turn it into a very well equipped all around zoom. Prior I would have said the 24-105 is the best all around zoom on FF, but I suspect now I'd take the Tamron instead. What I lose in reach I gain in light and it means on family vacations I don't have to also think about packing a 50 1.4 and/or flash. I did however hate the reverse zoom, but I can live with that and the extra $1000 in my pocket pretty easily.
ps love the field of dreams reference