I loved the last design for last.fm. The layout, site structure and general UI made the site a massively easy to use online social network music hub. I've been with last.fm for over a year, and have thought that the only flaw in the website was that it wasn't the fastest site on earth - but that is irrelevant in comparison with the features and simplicity of the site.
I've always loved the site - the community is friendly, and the developers and folks who work on the site keep in touch with the users with the blog - complete with ball pit cams. I think what sets last.fm apart from other music social networking site is the fact that in essence the bands and users control the site, and the last.fm were lucky enough to be funded at an early stage in the site. The CBS acquisition of last.fm has not noticeably changed anything to users, and if anything has been a massive advantage to the company.
The new look of last.fm was rolled out yesterday, and I have to say it has already been greeted with criticism by users in the forum, and on the new look last.fm blog post itself. Embarrassingly, the first comment the post is greeted with is "Whatever. How can i get the old layout back?! This is back to the 90ties." The comments on the post are now closed at some 2127 pieces of feedback - most to the tune of "How can I get the old site back?"