1) It originally only allowed facebook login, or rather thats the only thing I could find. Now there is Twitter, which is better... but it's still unreasonably restrictive here.
2) The music search is a nasty broken mess. It reminds me of searching for music in the very very early days of Napster... No, wait... Napster was better. I can't search for albums very well, I can't sort the results, I can't distinguish between a good quality song an a shitty quality song often. Especially noticeable when search a song name and getting a live track instead of studio track.
3) Something as simple as "Shuffle" never showed up. I hated having to manually shuffle my list of music. Usually I'd add entire albums at once... but I didn't want to listen to all the songs in order.
4) Starting a room is frustrating because you can't listen to music by yourself. There is no way to grow a new room from me, by myself, to 100 if I can't listen. I'll simply leave the room.
5) Needs a DJ recommendation service or something. I need a way to not baby sit my list.
All of that aside, I think their service would work well as a spotify app maybe. There are other similar spotify apps now that are much nicer to use.