The guy(s) who were playing Gilmour's parts did a good job, in general. But they weren't Gilmour, and they didn't stand on top of the wall to do the Comfortably Numb solo. I saw Floyd on their '87 and '94 tours, and Gilmour on his '84 solo tour. Also saw Waters on his '84 solo tour (with Clapton playing guitar! now that was cool).
Gilmour is a much better musician and singer, but Waters is a showman. They were great when they worked together, but that pretty much stopped after Wish You Were Here.
The best songs from The Wall are Gilmour songs (Comfortably Numb, Run Like Hell). Most of the other songs are vocal-heavy, which is kind of ironic since Roger has sort of a reedy voice. You have to think of it as a total show experience, and less as a concert. The staging and visuals were indeed amazing.
As far as concert experiences go, the best song from any of these tours had to have been One of These Days on the '94 tour. If we weren't already in a stadium, it would have blown the roof off.