I have been playing with it yesterday. I have been hacking some Perl and PHP to get Movable Type import to work property, so I can keep all the old stories yet not sending out wrong articles to those landed here via Google. First impression with WordPress is pretty good, until you actually look inside the code and database, then you'll discover all the spaghetti. Pretty much what I would expect from an open source PHP project anyway.
Also need to port mtsend.py to support WordPress dialet of XML-RPC calls, as most of time I just blog from command line.