BG1 is a good game, but IMO it's nowhere near the classic that BG2 is. The resolution is lower. The pathing AI is terrible. There's almost no inter-party dialog. Instead of jumping from site to site, you have to travel through large wildernesses slowly. Quests are more basic, and fewer in number at any given time. Maps are not marked for important locations.
Actually, I *like* BG1.
It has a lot of things to offer that I didn't mention. But everything it has, BG2 has more of, and the latter fixes all the problems I noted, above. BG2 is a far superior game.