"[Rumi is] one of the world's greatest poets. In profundity of thought, inventiveness of image, and triumphant mastery of language, he stands out as the supreme genius of Islamic mysticism."--A.J. Arberry
Out of the dozen or so different versions, translations, and interpretations of Rumi I've gone through, Arberry is still my favorite. Some say it's a bit stale with the literal translation, but that is far better than someone else's limited interpretation (like Barks or Harvey), especially when today's popular interpreters are unable to dive deep enough into Rumi and simply call him a mystic or a writer of Love poetry.
Arberry also includes some notes (though a full addendum is really required to begin to grasp the layers of Rumi), which are helpful.
If you do like the modern interpretations, at least read Arberry first. Then you can make up your own interpretations before reading someone elses.