Options for iTunes replacement
I know this is not very pro-Apple of me, but I would definitely recommend Google Play.  Unless you happen to have more than 20,000 songs, you can upload all your music to your own Google Play library, and then access it on any device.  I had used iTunes previously because I wanted a service that allowed me to easily access my music on any device, but since Google released an iOS app that problem was solved.

Speaking of which the usability of the UI on the web front end and on the iOS app in my opinion is great and very intuitive.  Searching is done almost instantly, and it also returns results from the google play store, which is super nice for me since I now have their streaming service. ($10 a month, otherwise Google Play is free)

Anyway, Google Play is a great replacement if you don't mind having your music pushed to the Google Cloud.  It also serves as its own backup...

The only issue I had when switching was with some of Apple's old DRM from a very early version of iTunes... I can't remember how far back, but the issue was only with a very few amount of songs.