Sims are extremely useful tools...

Using a sim I taught myself to fly a heli, and I was able to solo a plane on my third flight/tank. Typical newbies at my club that don't put in sim time spend a few months on the box before soloing... a couple of guys have been on the box for over a year!

If you're going to just play them as a video game, that's pretty much a waste... if you're serious about learning, though, they'll save you a lot of time and money in crash rebuilds and nitro costs...