They are an excellent social alternative and seem to be improving in taste. They are usually low cal, too, which helps in addition to the no alcohol.
As someone who is often the designated driver, and for whom alcohol can be a work-related problem, I find them to be an excellent way of socializing without the negative effects of alcohol. Yes, they lack the “social lubricant” effect that alcohol has on some situations, but the trade off is well worth it in my opinion.
In short, for me, they can be a very good alternative, if not necessarily the 100% change solution.