The security assessment is for the Windows version of TrueCrypt only. Which also answers your question, TrueCrypt is appealing because it works on *nix, BSD, and Windows. It is also free and open source. The Windows version is easy to use, has a nice GUI and actually works as stated.
https://en.wikipedia.org/wiki/TrueCrypt#Licensing_and_Open_S...
Wikipedia lists it as "source-available".
TrueCrypt for example uses fixed and low pbkfd2 iteration counts as specified in the report.LUKS on the other hand uses adaptive pbkdf2 iteration count number that goes up automatically when a LUKS volume is created on a faster computer.
The appeal of TrueCrypt other than portability atleast among linux users is an easier to use GUI.Fortunately, there is a project called zuluCrypt[1] than supports TrueCrypt volumes among others and has a GUI window that is comparable to TrueCrypt's GUI.
If you are a user of tombs,zuluCrypt can also open tombs through its "gpg" and "tomb" plugins[2]
[1] http://code.google.com/p/zulucrypt/
The questionable license, and obscure nature of the project should be significant reasons not to use Truecrypt. That doesn't even begin to consider the actual security of the program.
Everyone always talks about Truecrypt which is clearly most popular but both of the above are fully open-source. The latter is even part of the kernel. I'm curious what the appeal of Truecrypt is besides maybe portability (which is a pretty strong selling point).
[1] http://www.dyne.org/software/tomb/
[2] http://ecryptfs.org/