The original novel trilogy is the best thing Dragonlance brought us, IMO. That set a bar that game fiction still struggles to reach most of the time. The only game fiction I'd put above Weis and Hickman's original novels are Ray Feist's Riftwar books, which aren't technically game fiction. Even though they really are.
It's not necessarily great compared to non-game fantasy fiction, but it still holds its own. Plus, it focused in on dragons again, at a time when the game Dungeons & Dragons wasn't really. I'm a little over dragons now, but it was cool at the time.
Also, Dragonlance was the vehicle for the so-called "Hickman Revolution." Which I didn't think was necessarily revolutionary, because I was already doing things that way (and in fact had become quite disenchanted with D&D for not), but it changed gaming culture I think, and for the better.