Why should you read him?
1) He's one of the best prose writers in fantasy - better than Mieville, roughly on a level with M John Harrison
2) He is hugely original
3) He offers something for everyone. I'd be very surprised if someone was able to read City of Saints and Madmen and not find something they really enjoyed. Vandermeer's short stories/novellas in it are hugely varied - it was hard to believe that it was the same author. He ranges from very dark, urban type fantasy to postmodern fantasy to humorous fantasy. Vandermeer also likes challenging the reader's assumptions (not just about fantasy but about fiction in general).
I'll do a brief (non-spoiler, of course) analysis of City and Saints and Madmen:
It starts with Dradin, in Love. This reminded me a lot of some of Harrison's Viriconium sequence, but in many ways it was a more cynical version of it. A lot of originality, very good prose, and while the ending wasn't unbelievably surprising, it was certainly shocking - something that you were expecting, but wish it didn't happen. Very, very good characterisation. It's some kind of mix of Harrison's Viriconium and Clark Ashton Smith - lots of horror in it, a bit of humour, lots of imagination.
Then comes A Short History of Ambergris - very humorous, but disguising a very dark history underneath the city. It's a very clever way of doing the essential worldbuilding for Ambergris. Very readable, and as Vandermeer is a postmodernist and believes all history is a fiction, you can guess his take on it.
Then the Transformation of Martin Lake - a similar style to the first one, but with a new plot, new characters etc. It works very well, but not my favourite of them.
The Strange Case of X - metafiction, with an alter-ego of Vandermeer in it. A very Kafka-esque story.
King Squid - a series of essays on the Ambergris squid. Again very humorous and giving a lot of insight into the world of Ambergris. Had one of the best bibliography's I've ever seen.
Then there were a number of oddball short stories after it. I think Vandermeer's one of the geniuses in speculative fiction at the moment, perhaps just having the edge over Mieville - his prose, plot and characterisation are a bit more consistent and well done throughout. The only problem for me was the short story format, which I usually don't like, but Vandermeer's definitely one of the best at this and it worked very well.
So if you're looking for imagination, originality, excellent prose, humour, decent characterisation and a dark tone, Vandermeer's about as good as you can get. I haven't read Veniss Underground yet, but I'm looking forward to it. Basically, if you like Mieville and Harrison, you'll almost certainly like Vandermeer.
