I have seen a few of these aircraft fly at the local club, and the general consensus is that it is not as great as a "proper" trainer. It lacks any self righting ability, and is also a taildragger - landings and takeoffs will be more difficult.

If you are planning on learning by yourself, forget the Mustang. When (not if) you crash, you could do major damage. Get a smaller glow trainer, such as a Carl Goldberg Eaglet, or Sig Kadet Mk2.

For learning to fly a glow trainer, you really should join a club - at least so someone can look over your aeroplane and test fly it.
From my personal experience, I think the Sig Kadet Senior is the best trainer. It looks great - rounded forward fuselage, real windows, and a fibreglass cowl. It is also a good size (80 inch wingspan) so it is easier to fly. (trust me - smaller models are harder!)

Have fun and enjoy the hobby!

Graeme