If anything, my opinion of it now is even greater than that initial "Wow, I've now got 6 million tracks in the palm of my hand" that I had when it launched. I use it multiple times daily, using both the offline cached tracks and online streaming. This app is simply superb. I've had fantastic fun both catching up with albums I hadn't yet listened to and also discovering new-to-me artists that I'd probably not have otherwise bothered with.
The offline functionality is very good. If I've got a large selection of tracks I've selected during the day for offline use, I just fire up the app when I get home and it'll download everything for me ready for the next day. If you start the app, you can switch the iPhone off and it'll continue downloading.
Another great service with the Premium Spotify account is the access to pre-release tracks and albums.
This is a keeper. I'm having great fun listening to all sorts of new stuff, as well as my favourite oldies. The service and, in particular, the sound quality, is quite superb.
Well done Spotify!
I've still got a couple of invitations left, so leave a comment if you're interested.