Drivel has pretty good features, support for several blogging platform standards including Movable Type / WordPress, LiveJournal, and Blogger 1.0 & 2.0 (Atom). The user interface is clean and simple but has decent formatting features.
It doesn’t show WYSIWYG but uses syntax-highlighted HTML instead. This isn’t always a bad thing, as it means you’ll always be able to hand-edit your post. But beginner users that don’t want to know HTML may need to adjust themselves a bit.
I think there aren’t much good (and advanced) blogging clients for Linux and Drivel is really a nice one. If you’re looking for more features you may want to try ScribeFire (Firefox extension). Though ScribeFire has some formatting issues, and it’s a Firefox extension which can be both good and bad thing, but most importantly it works (and incredibly well.)