I use iTunes Match to manage my music across all my devices. It works well and has been pretty seamless for me. Well worth the $25 a year.
Recently I took a short trip to Africa and wanted access to my music while I was disconnected from cellular and wifi while I was in the air, so I took advantage of the ability to download music to your device (iPod, iPhone, or iPad) by clicking on the "download all" from cloud option you can see from playlist, artist, or albums while in the Music app. This made it easy to load up my iPhone with hours (days actually) of music. Wonderful, right?
Well, I am back now and I’d like to free up space on my iPhone for apps. Guess what? There is no option to remove songs in bulk from your device. As far as I can tell the only option I have found to remove music from your device is go to the song you want to remove, swipe to the left and click on delete. And you have to do this one by one for each song you want to remove. So what took only a few minutes to load on my iPhone is going to be very painful to undo.
If you know of an easier / faster way to remove music that has been downloaded locally please let me know (and yes, I know I can recover from an old back up, but I am looking for something cleaner than that if possible)!