It sounded good to me also, the reality wasn't quite as I hoped. Naively I thought I would be able to play these downloaded tracks through a separate media player as part of my existing music library, which you don't seem to be able to, and the Deezer app is quite limited when it comes to playback options. For me it's just been a way of previewing tracks to see if they're worth getting hold of.
In saying that, the wife loves it, and uses it constantly.