If you use the sim as a tool it will help you develop reflexes needed fro flying.

I started learning without one and wasn't getting on very well. I bought a sim and couldn't believe how much it helped me develop my flying. I practiced all last winter on it doing loops, rolls, and flips. When I went out last spring I was able to start doing them for real immediately and know it was all due to the sim practice. I couldn't believe how close it was the doing them on the sim. I now practice all my moves on the sim before putting my $1000 machine in jeopardy.

I wouldn't recommend that anyone start without one. It's one of the best items on a beginner, or experienced pilots must have list.