I'm a huge fan of his ever since Reality Dysfunction was released back in the 90s. The worst thing about his writing is that he tends to produce long books that are part of a series. This is great if the series is complete, like the Night's Dawn trilogy is, but when you pick up the first book in hardcover, and pour through 1200+ pages of luxuriously described people and places and then discover the next book won't be published for another year, it's a bit like having become an addict and then being forced to go cold turkey.
When Pandora's Star, the first of the Commonwealth Saga books was released in 2004, I left it unread on my shelf dying to read it, but waiting for the release of the sequel, Judas Unchained. For months, it called to me, promising a creatively crafted universe of fascinating people and amazing events. Not a single day of the ensuing year passed without knowing the book was there.
That whole ordeal was so tortuous that I gave up any pretense of self-discipline and immediately read The Dreaming Void as soon as it came out in 2007. The final book of that series will be published, as Candlelight notes, in August.
Hamilton is my favorite living SF author. He writes amazing stuff that combines space opera with hard SF. His characters are almost always engaging and do things that leave me breathlessly excited about the future. He deftly picks up ideas involving nano-technology, genetic engineering, alternate universes, and space travel and weaves them together with new sciences and original ideas of his own creation. He's like putting Arthur C. Clarke into an atom smasher and slamming him into Larry Niven at the speed of light, then entangling the resulting particles with Isaac Asimov ... he's ... brilliant!
I can't recommend him enough.