I've been in the beta for a couple of months. It's a pretty good deal - in my area the $10 plan either gets me 3 matinees, 2 evening shows, or 1 weekend movie. Tickets to my theater are $9.95 for every showing, so it's an okay deal and usually nets me a couple of theater trips a month for my $10. Basically, half price tickets. If I go to an evening show on a weekend, it's break-even though.
Your individual results may vary, depending on how many points the movies near you cost with Moviepass compared with how much ticket prices are.