They were very good at the art of making games, but terrible at business from just about every other angle.It's funny - when I think of the old TSR I think of two different companies - there was the TSR that created some of the games that defined my youth that I have a lot of fond memories for. I kind of miss that company. Wizards is a good steward of D&D but they're never going to produce something out there like Mertwig's Maze or Gangbusters - that's not the kind of company they are.
But then there was the T$R that destroyed other gaming companies via litigation and went around threatening to sue fans for publishing fan created materials. I don't miss that company at all.
Funny enough they were the same company - it wasn't even like there was one era when they were good and another era when they were horrible. They were both simultaneously.
In conclusion, TSR is a land of contrasts.
One of the most shocking things I've heard was that TSR R&D never received sales feedback until they were folded into WotC: they were simply never told when a product sold well or poorly so they could adjust to the audience.