Sim are an enourmous help. Not only for beginners but experienced pilots as well. I used a sim when I was learning how to fly. It gave me stick time that is critical to learning. Later, I used it to correct a bad habit I had after exiting spins which caused my real plane to crash. I also used it to learn slow rolls, rolling circles, rolling loops and torque rolling. The sim isn't perfect, and it doesn't alwasy properly represent what a real plane would do, but it is close enough that it represents a great tool every pilot should have.

G2 is good, but there are other sims available, such as Ikarus, Dave Brown, etc. I think there are even some free ones if you hunt around. Even a free, not totally realistic sim will offer useful stick time.

Cheers!