I've had a few for about 2.5 years, and I think they look very good. The materials they have come out with for them are much better than those in the past. (In fact, a couple months after I got mine my dentist remarked that an even newer marterial was available). I do have a history of grinding my teeth, so I have to wear a bite guard every time I go to sleep. Before we knew how bad it was, I actually chipped one while I was sleeping before I got the guard. Luckily, the dentist replaced it for free although it wasn't under warranty or anything.
However, if your smile could be fixed by braces, I would strongly recommend that route. Do not use veneers as a quick fix. In my case, even with braces, I would not have liked my smile. In my case, a few of my teeth were smaller than what they should have been.
Just remember if you go with veneers you can't go back because they have to shave your teeth. It is a permanent desicion.
Edit: As far as speaking and biting...it took a few days to get used to it. When I first looked at them after I had them cemented in, I thought they looked awful! However, it was just because it was so different. My teeth look 10 times better than they did before.