Windows Phone 7 missed out on some of the best features of the Zune HD. With Windows Phone 7.5 Mango, you can finally make your own playlists.
You can also get a Smart DJ mix of music on your device that should go well together, or even music from the whole of Marketplace if you have a Zune Pass.
Unlike Google Music, this actually provides tracks you want to listen to together rather than strange and jarring transitions, especially if you're streaming tracks from the huge choice on Zune.
The player controls are also a little larger and easier to see (although possibly not as elegant), and they show up on the lock screen as well.
For video, assuming the file is either local or a format that can be cached, you're provided with a progress bar to scrub through the media as well.
The other big missing feature of Windows Phone 7 was custom ringtones. The Mango update means you can now add these through the Zune software, with unprotected tracks of less than 40 seconds that have the ringtone genre assigned to them. It's a clunky mechanism, but we expect plenty of apps to appear making this painless.