I was very unimpressed with Spotify when it launched in the US this week. The app (at least on a Mac) seemed very non-native and used a lot of resources when it was inactive. It apparently uses Flash, so that may be it. It can't connect to my speakers, though that's Apple's fault more than Spotify's (AirPlay). I saw some top music lists, but not much else. My iTunes Playlists sort of came over, but not the Smart Playlists which are the only ones I use. Didn't see any recommendations.
tl;dr I closed the app and haven't listened to any music with it.
I strongly encourage you to give it another try. Spotify is not iTunes or Pandora, it has very different strengths. At least here in the UK, it streams insanely quickly, streaming starts immediately and the size of their catalogue is simply incredible. You might still find that you don't like it in the end but I wouldn't give up on it after five minutes, really.
Also, just to clarify a few things: it's not based on Flash. It's written in C++. It uses Ogg Vorbis. The user interface closely resembles iTunes so if you're familiar with that (many people are) Spotify shouldn't be too confusing.
Disagree. Been using Spotify for 1,5 years. It is a native app on OSX, feels native and does not use a lot of resources (have you tried this app called iTunes??). They do use flash for ad's though so maybe that is the problem, I pay for the premium account which does not have advertising. For connecting to my speakers through airport express I use the excellent AirFoil app.
tl;dr I closed the app and haven't listened to any music with it.