I generally prefer to do things on the command line when I can. Mplayer is a great tool for playing all sorts of media, but the command line interface sucks. Some things I'd like to see in a CLI wrapper would include:
- Clean output - easy to understand, not cluttered by a bunch of stuff that's irrelevant in day-to-day use
- ID3 information
- Progress bar & play time info (total time, current time, time left)
- Play queue - list of songs with lengths and an indication of where you are currently