Tigana is a classic and I've got most of Kay's work. Certainly a significant contributor to SFF.
AMEN TO THAT! His writing is really beautiful and elegant, though, given his incredible quality, I hated Ysabel. I hope his next offering, which should be available soon, returns him to form. Anyone who likes fantasy should try Kay. Also, he has eschewed any kind of big epic series since his debut in the Fionavar Tapestry.