I use Mountain Lion on my 13’’ Macbook from 2008 and it works fine. Yes, there are some hiccups and it is not always running smoothly, but I’m glad that the changes of OS X can still be applied on such an old device. I went back to 10.6.X and 10.7.X several times and missed some essential features of their respective successors and updated rather quickly.
Interesting move if the rumors are true. Especially after the redesign of Flickr yesterday. What I also would dig would be a deeper integration with Tumblr or perhaps Wordpress?
Never used the app and I have no intention to even try it. The article proves that #Music was/is an overhyped service that failed to meet the expectations by critics and users.