Finished Vineland finally. It lacks the scope of Gravity's Rainbow or Mason & Dixon, which is probably why it'll never be considered one of his major works, but it's pretty much on the same level. It's his most personal novel and his most incisive. Very sad and nostalgic - and angry at the current state of America (in the 80s).
I'm reading it on the basis of this comment, now halfway through, and I really have to disagree with this. I think you may have forgotten just how great those two novels really are. There's hardly a wasted sentence in Gravity's Rainbow, whereas in Vineland I feel like I have to wait and wait and wait for the good ones, and when they finally come they just aren't good enough. I never finished Mason & Dixon but the little I read of it was way better than this. It's definitely Pynchon's hollowest book, imo.
Edit: I should also say that I recently bumped into someone in Barnes and Noble who was looking at the Pynchons (I was looking for the latest Roth) and we struck up a conversation. We got to talking about Pynchon's novels and of course eventually started giving our respective rankings, and he placed The Crying of Lot 49 at the bottom. This is an opinion I seem to encounter more and more, sometimes given with good reason and sometimes given with bad, but as I started defending the novel it became clearer and clearer to me that the guy had just rushed through the book without thinking about it at all. Now, I don't expect anyone (especially anyone my age) to read with the Nazi-like rigor that I have adopted, but this guy didn't even know what the "lot" of the title referred to. Didn't have a clue. How can you read a book by a guy, claim he is your favorite author, and not know what the fucking title even means? I had always read about and seen in movies characters who would pretend to read certain novels just to seem impressive, but in real life the phenomenon is even more deeply horrifying than anything in my wildest imagination. It's not horrifying because "Oh I am a better reader and my sensibilities are offended by people who can't read well". It's more of a sadness. Why do people waste their lives doing things that they don't want to do? Yesterday I read Whitman's "The Sleepers" and it sent me into the highest ecstasy. That's why I read. Because it's a powerful experience. I urge everyone in life: never pretend. If you don't like reading novels then stop reading them. Be honest with yourself about what you do and don't like, about what you enjoy reading and don't enjoy reading. Do not lie to yourself. And that is only the starting point. Life is too short.