This is exactly what I was looking for, I have no complaints so far. A million times better than Papers, and everything is free (unlike Papers for PC). I do hope it stays free or for a very minimal fee... starving student and all that! My only recommended improvement would be to allow creating a bibliography without pulling from in-text citations, i.e. ticking a list of which articles you want, and then a button to compile... rather than copy/pasting citations one at a time. That said, the MS Word extension is fab for what it does. :)
kymbeee about Mendeley (PDF Reader), v2.9.2