Some of the music on Pony.fm seems to literally take forever to download as Ogg Vorbis. This is a particular pity in the case of music that was obviously uploaded as Ogg Vorbis and re-encoded (= compressed lossily once more) by Pony.fm.
For example, when I tried to download "Don't Forget" by Donn DeVore, I got the usual message "We're getting your download ready! This'll take a few seconds." What should happen is the download actually starting after a few seconds. What actually happens is nothing more. The message remains (and I've left it running for at least 10 or 15 minutes sometimes, if not even longer), but no download starts.
I've only tried material from times when lossy uploads were still possible and from imported archives. I haven't tested it with lossless updates because why download Ogg Vorbis if you can get the good stuff (FLAC), so I can't say whether these are affected, too.