I'm a beta subscriber of last.fm so I've played with the new beta design and I think it works pretty well. I was never a massive fan of their pink design, the new one is a lot more clear and clean. The navigation could be sorted out a little but apart from that, it looks good.
The new features they are proposing are great. I don't use Last.fm much but I like to browse the various areas like Events and Artists to find new music. The addition of Podcasts sounds intriguing as right now I mainly use iTunes for them but that's not very portable.
