I expected a three course meal, and they gave me a lunchable.

I share a lot of hmorsey's opinions, actually. While, yes, the episode did have drama/funny/romance, that does not mean that it was good. Every episode has drama/funny/romance (other than the shooting episode, which is not a bit comical). The drama, to me, seemed like a daytime soap opera which is not good. I mean, seriously? Who did the background music for this episode? It's like it was straight out of Passions or Days of Our Lives or something. The return of Nanny Carrie was completely unoriginal and terribly orchestrated.. the only thing that saved that plot line was Bethany's excellent acting. As for the funny, the episode was definitely lacking-- although, honestly, that doesn't bother me much because that isn't why I watch OTH. I did like the Ross/Rachel reference, though. And don't even get me started on the romance. The Jewels/Keith wedding was so much better than the Lindsey/Lucas one. And seriously... Peyton's car is the comet? Liked the flashback, hated the reasoning. They could have stuck with the comet simply being Peyton and I would have been more satisfied.
I would much rather the library episode have been the 100th. More memories, less cheese.

Well, I guess this gives me room to elaborate on why I believe that the library episode would have been a better choice:
First off, the 100th episode should concentrate on memories. Let me possibly bore you with examples: in Angel, Cordelia was brought back; in Buffy, Buffy dies which instantly sends you a thinkin'... and of course, the tombstone that said "she saved the world, a lot"; in Smallville, Jonathon dies, the Clark/Lana relationship reaches its peak.
But what will I say when I think about One Tree Hill's 100th episode? There's a predictable end to a wedding, nothing gets resolved with Naley. Honestly, a couple years from now, I might have to think about which episode it even was. Maybe I'm being unfair because of how great the episodes have been so far this season? I don't know.
But the library episode would have concentrated on everything that a 100th episode could have (although I would have expected a little more out of it if it were the 100th). First off, it revisits the shooting episode-- possibly the biggest ep of the entire series. Then, it brings back Tim! I loved that! And when everybody is singing Mia's song, it's priceless.
Is that too much to ask?