I've grown accustomed to the Music app, but I do wish it was more full-featured in terms of things like generating radio stations from genre, etc. But, Microsoft's Xbox Music does have a great selection, probably second only to iTunes (and much better than Google Music, in my opinion). I do subscribe to Music Pass, but wish discoverability were a bit better...
Import should work fine, and if you subscribe it will match your songs and make them (or whichever of them are in Microsoft's portfolio) available on all of your machines (if you don't subscribe, your music will still be available on all of your Win 8.1/Win RT machines). It's not a music locker like Google Music, however, which will upload all of your songs and make them available regardless of whether they're in Google's portfolio, but it's still pretty nifty.