I really like iTunes. In general it is easy to use. Unfortunately it does have some short comings and my experience with Magnatune showed some of them. Specifically, iTunes handles m3u play lists badly and it can't handle FLAC files. But thankfully there are somewhat reasonable work arounds.
Magnatune makes all of their music available as free MP3 downloads so you can try before you buy. They use m3u files (e.g. play lists) to provide access so the MP3s. Unfortunately iTunes opens a m3u file by just dumping all the music listed in the file into the main iTunes library and then playing the first song. Unfortunately the songs are now in 'library' order so the next song played will probably not be the next song in the m3u list, meaning I have to hunt around the library to find the rest of the songs. This "hunt and peck" also makes deleting files a real pain if I decide I don't like the play list.
Thankfully there is a fix, iTunes Opener. Download the file, uncompress it and drop it into the Applications directory. To make sure that iTunes opener is always called when clicking on a m3u file you have to go to the finder. First, open the finder, then select a m3u file, then go to file->get info, then go to "Open with", select "iTunes Opener" and then press "Change All…". What iTunes Opener does is open the playlist as a separate group in iTunes and gives it a default name of the current date and time. This allows the play list to be played in order and makes it easier to delete an unwanted play list (just drag it into the trash).
Ahh, but the fun doesn't end there. Magnatune offers a number of download formats but from a quality perspective WAV and FLAC are best since they are lossless. FLAC is preferred as it is both an open format and usually around 1/2 the size of a WAV file but with no loss in quality. Unfortunately iTunes does not play FLAC files. Since I don't want to waste the time downloading WAV files I choose to download FLAC and then use xACT which can translate between FLAC and AIFF or WAV. AIFF is Apple's lossless music compression format and is supported by iTunes. Unfortunately xACT can't seem to maintain the FLAC tags (e.g. album name, music title, tract number, etc.) on the AIFF file so when the file is imported to iTunes all the tags are lost and have to be typed in by hand. xACT does have a "FLAC tags" tab that allows one to read the tags on the FLAC files but I still have to select the song in iTunes and then select File->Get Info->Info to type in the data. It is really annoying.
BTW, Magnatune happily allows downloading AAC files which are iTunes native compressed (hence lossy) format as well as a Mac friendly MP3 format, Ogg, etc. FLAC is not some strange format and I think it was a bad call on iTune's part to not support playing FLAC files or at least support importing them into the AIFF format.