On K5, there's a piece on Why my Moveable Type blog must die - well not mine specificially but MT blogs in general. Some of it is Andrew Orlowski style blog bashing, pointlessness defined, but there are good points also. The best one is that MT is quite brittle and inflexible when your page demands start to grow or you desire some kind of CGI interaction. It is a problem with MT that the Admin interface isnot built from the same templating system as the MT blogs themselves. That is quite a nuisance when MT's data model becomes to constrained for your needs. There is even an unclean separation between blog and admin system: Error messages on mailing errors are delivered by the admin system and not your blog, so you need to hack in an ugly interface breaking way to do "branded" email from MT.