I love the sim. I can tell you I would never have learned to fly inverted without the sim. At the field, I'd roll over, and immediately panic and roll back. So I spent maybe an hour or so with the sim, until the panic eased. When I got to the field, the plane behaved almost exactly like it did on the sim. Personally, I'd rather practice out on the field with a real plane, but if you have the patience and dedication to stay with the sim (which I find very boring), you can definitely learn a lot.

I agree with FHHuber that the sim is less useful for landings and take-off, which is really what a beginner should be concentrating on. For those skills, you need to learn to estimate air speed, ground speed, and orient the plane with the runway, none of which the sim helps much with. Another thing the sim doesn't help much with is seeing the plane. At the fields where I fly, the sun can hit the plane in a way that makes appear to reverse orientation (I call it the Escher effect). This is REALLY disconcerting for a beginner, and the sim doesn't really help with it.