There's no help file or tool tips for aTunes, but if you have any experience at all with other players, it's easy to figure out. My only moment of confusion was with the repository pane--I didn't immediately ken if I was searching for repositories where files existed (I was) or defining one where files would be stored. Otherwise the interface is very intuitive. You simply define that aforementioned repositories where the files you want o play are found, the program grabs all those it recognizes, then you drag them from the resulting list to a tabbed Playlist pane.
aTunes handled most of the file types I threw at it, including Real media, lossless .flac and .ape files natively, i.e., without DirectShow filters for those types installed. On the other hand, it wouldn't recognize or add Apple's AAC files. It also played 24-bit .wav files too fast and with a warble. It played 16-bit and 32-bit wave files perfectly, so this is an easy fix that you'll probably see soon. Playback was otherwise rock-solid and I never managed to crash the program. If you're looking for a cross-platform alternative to iTunes, aTunes is well worth a look.
Note: This link takes you to the vendor's site, where you can download the latest version of the software.
--Jon L. Jacobi