I've only seen Blood Rayne and it wasn't bad but his stuff isn't as bad as Bay's in my opinion.
Ehhhhh, I dunno, I don't think you've seen enough of Boll's work to realize just how horrible he is. Bay isn't great by any means, but he's still better than Boll. Boll apparently has a thing for taking great video games and turning them into laughably crappy movies. Here's a short list of some you might have seen/heard of:
House of the Dead
Alone in the Dark
Bloodrayne (he also directed two straight-to-DVD sequels)
In The Name of the King: A Dungeon Siege Tale (yes, a movie based on DUNGEON SIEGE :angry)
Postal
Far Cry
All kick ass games, all horrible, HORRIBLE films. I almost want to tell you to watch all of them, just so you can understand how awful of a film maker he is. But I'm not sure if you should subject yourself to that kind of torture.
The only Uwe Boll movie that's actually any good is a film called "Rampage", which thankfully has nothing to do with the classic arcade game. It's currently on NetFlix, I'd recommend checking it out when you can.