You still need arrows, at least you did in Oblivion.
Another thing is that if, for whatever reason, you've been separated from your inventory you still have a bow (SI Prison).
I'm not so sure about that in Skyrim.
If you've seen the picture (which I can't link for obvious reasons) the arrows/quiver are also very ethereal looking. They are the same clear blue color as the bow.
You may have finite arrows this time, but more damage from it or some trade off. (set number when summoned)