It's easy if you play the harmonica, but some people get confused by the different not for each direction of air flow. And there are a lot more melodeon players than the ones who use it to accompany songs. Although I do that, I find it's a lot easier to use my bouzouki for song accompaniment. Now that's a lot easier than guitar as well, and it doesn't hurt your fingers (a surprising number of would-be guitar players give up because of this!).