I'm also a big fan of ClearView, which can be downloaded at http://www.rcflightsim.com and used as a demo on your PC for 15 minutes to test compatibility.

I own RealFlight G5.5 (I started at G3.5 and have upgraded a couple of times) and I like the simulator, but I don't know too many folks that claim it's superior to the other simulators as far as a learning tool. It has some cool multiplayer features and a nice selection of planes, but too much time is spent marketing Real Flight instead of improving Real Flight, in my opionion.

Certain nuances of RC flight are modeled more realistically on the other flight simulators. Trainer slow flight, helicopter flight characteristics, and indoor flight are just three examples where ClearView is better than RealFlight G5.5, in my estimation.

Real Flight has gotten better over the years in some areas. I remember thinking it was weird that a Nexstar trainer would drop like a rock if you cut the throttle back to 2/3rds full on the simulator, but the real plane would want to glide forever even if you chopped the throttle back to idle. The slow flight characteristics of trainer models has improved considerably since G2 Nexstar Edition/G3, but it still doesn't feel as natural to me as the physics and flight modeling in ClearView.

Helicopter flying is something I'm still relatively unskilled at. I have a Thunder Tiger Mini Titan e325 450-class electric heli, and the day that it arrived, I also went out and bought Real Flight G3 Expansion Pack 4. It has the Mini Titan as one of the new models, and it's rendered beautifully right down to the holes in the wooden rotor blades.

I've gone out and put 4 or 5 batteries through my real Mini Titan out at the field, then come home and tried to fly the Mini Titan on Real Flight G4/G5.5, and I haven't been able to do it. The flight modeling and physics are so far off that the simulator model is nothing at all like the real thing.

I've owned some of the Flat Out foamy models in RealFlight and I've flown them in gymnasiums and indoor sports facilities before. When I try to fly the same plane in the same kind of environment on RealFlight, it can't be done. Again, ClearView's physics and aeromodeling of this kind of flying simply feels more natural and more like the real thing.

Registering ClearView for $39.99 and getting a $19.99 ESky USB controller box will give you as good of a training tool as anything on the market. You can spend more, but you'll mostly be paying for fancier graphics and marketing costs. My second choice for "bang for the buck" would be Ikarus' EasyFly 4 simulator. It's available directly from Ikarus for $99 with a USB controller. Either of these options will be as good of a training tool as the much more expensive simulator packages available today.