It's good.

Typically you use TrueCrypt to make an encrypted block of data that resides in a file of your choosing. All your data is relatively safe, but anyone with write access to your drive would be able to cause you trouble by messing with the file itself (moving/deleting) but they'd have to know exactly what to look for (TrueCrypt files are unidentifiable by any signature or header information). You can even have encrypted volumes inside one another that are undetectable (one file on your hard drive could have 10 layers of separate encryptions and no one would ever know about the interior volumes). Even if someone gets your password for the first layer, they'd have no clue your truly sensitive hidden data was 9 passwords away.. Etc..