I'm of two minds with Civ3, I keep starting up games and then getting bored half way through.
I think the problem is that while Civ3 has some major improvements in terms of graphics, interface and AI, much of the game is the same as Civ2 and a few bits actually regress a bit.
The problem is that despite the fact the game looks entirly different, it plays like Civ 2.5. There is little in the way of new material to learn.
The new resource and trade system is the only major new game mechanic, and it's not that complex. And there a few bits that have been simplified.
As for bugs and slow interface, well that has been true of all the Civ games. As a matter of fact, almost all of the Sid's game show the same problems. They don't seem to have a well designed internal architecture, but instead are built up on the fly. This is part of what makes them so fun, but it also makes them buggy.
Jay