I have only been using Invisalign for two months now and already see improvement. I always had straight teeth, but I've noticed crowding the last 4-5 years. Now 50ish..I decided that if I "have to" get old, I don't have to have crooked teeth too.
It is definately a life style commitment while going through treatment. My experience so far has been very minimal discomfort after changing each aligner. They're tight after I first put them in at night and fine by morning. It's true..very few people notice I'm wearing them and I work in a corporate environment.
The final results are yet to be determined.