A sim is a GREAT way to start out. The only reason I wouldn't suggest a sim initially is that a chopper in a sim is going to be trimmed out perfectly, whereas a real world bird wont be. There's a difference in flight between the sim world & real world that just can't be learned any way other than getting out and practicing. This is also why I wouldn't suggest TREX to a beginner. A nasty crash in one of those birds can set you back a few hundred dollars. Start with something inexpensive to learn on and THEN move up to a higher dollar machine.

VinceHerman makes a very important point about the coaxial birds... any wind at all will blow it around uncontrollably. They're excellent for indoor flying and outdoors on very calm days. Also, they aren't meant for any sort of abrupt maneuvers as blade clack is almost too easy to achieve and it'll drop your chopper out of the air like a stone.

Another thing to consider is looking into the RADD method. If you've never flown a chopper before, sim or real, his method of learning will save you many broken blades & bent spindles/shafts.