Let me first declare: I'm a mac user since 1985 but not a nerd, only enthusiast.
I have used and tested lot's of pcb cad softwares, Mentor, Pads, Cadence, Altium, RUN, and many many more and also EAGLE.
Altium looks really fresh and tasty. Mentor and Cadence feel a bit vintage and Eagle is a but less vintage but still it could need some face lift. Using EAGLE at a mac looks really ugly compared to how a normal mac software looks like. My suggestion is that Cadsoft hire some clever icon master.
http://iconfactory.com this is a good place.
Despite this small remark I'm glad that it's possible to run a decent pcb software natively on Mac OSX.