I've been using this site since I first posted the link. I now have 5 artists as the 'seed' for the types of music I like on one 'station' (not similar artists either). I have clicked a few times to say what i like and what i don't as it plays.... and it learns well!
Around one song in four is someone I listed, the others are often artists I would never have thought to listen to - and I like 95% of it. the other 5% gets the thumbs down and it learns
The site is not officially available in the UK so I won't be subscribing but i could see me being willing to pay a small subscription if it were. So if you didn't try it the first time round have a go and see how it improves as you tell it what you like or don't.