Just looked at these again in the store. Not sure what to make of Gooroovster- since the update last week there a dozen reviews alternating between 4/5 star and 1 star. What the hell? I think we need some kind of review template that includes details about the phone model, OS, network/carrier, and user's location. Seems like the same deal with CloudMuzik (note the spelling with a "z" ; spell it with an "s" and you get taken to "Cloud Music" an app that taps into music files in your SkyDrive account). Anyway, this one also has a frustrating mix of 1 star and 4/5 star reviews. These things seem to either work really well or not at all. It would be really nice if the dev could troubleshoot this and provide some feedback as to what the problem is.
Still not feeling inspired to try any of these, although GooMu seems to have the best reviews.