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.