My general rule of thumb is: don't trust a cryptography tool that has a catchy name. TrueCrypt has always creeped me out for that reason. Or maybe it's the idea of a "downloadable" filesystem (ok it's not technically a filesystem) driver that thinks it can run on more than one operating system and still do a good job of it.

I've never seen what's wrong with dm-crypt. It just works, and is mostly transparent.