I read one of Marvel's phonebooks this summer for a '70s run of The Avengers by Steve Engelhart that I'd remembered fondly from the days when you had to scour for back issues. Unfortunately it didn't hold up that well, and the B&W version can sometimes be a drawback for team books with crowded panels.

I'd guess that some of Kirby's work might suffer in B&W -- the art itself would hold up, but he strikes me as someone who very much drew with a sense of a color end-product in a way that, say, Adams doesn't so much. But I'd love to go back and read through the Lee/Kirby Fantastic Four some day. And Kirby's New Gods & sister titles are well worth your time (including his run on Superman's Pal Jimmy Olsen).