We used his Fall of Imperial China as a text when I was an undergrad, and The Great Enterprise was one of the first things I read in grad school. Great Enterprise was typical of his work, in that it was on a really big scale. Not just that it was a big book (although it is), but because it took on a big issue and tried to deal with it in the most comprehensive way. Future historians who want to know what the field was interested in at various points could do worse than to look at his titles, which ranged from the early Qing to the Communist period and across a wide range of approaches.
I only met him a few times. The first time I saw him was when I gave my first ever paper, at AAS. It was in a room that held about 300 people. There were maybe 8 people there, but Wakeman was one of them. After he was pointed out to me I dialed my goals back from impressing the audience to not embarrassing myself, which I suppose I managed.
This is a great loss to the field of Chinese history. I have benefitted a great deal from several of his more recent works on republican and wartime China and Shanghai in particular.
I had a chance to meet him this past spring and I thought he was a very warm, funny, and engaging scholar. He took time to meet with all of the grad students in our department studying China and was genuinely interested in talking with us about our respective projects, offering advice and suggestions where needed. A really great guy.