The 300 is a good reliable trainer. The problem is that it teaches out of date technique - airspeed is related to pitch attitude. All more modern helicopters, including the R22 require the attitude change to accelerate/decelerate, then re adopt pretty much the original attitude. The biggest problem operating the R22 in reality is its limited payload. The current generation of pilots are bigger and heavier, leading to C of G problems and having to seriously limit the fuel load.
The best trainer now is the R44 as with two up it has no fuel load limitations and is totally representative of modern helicopters. Obviously the ideal is to go straight to the 206, but is seriously expensive.