I've been a member of Curves for over a year now. Haven't lost much in lbs, but have lost some inches, but I haven't been trying all that hard so I'm not a great example of how well it really works. They're a circuit gym- the machines are set up in some circle fashion and they play music that's upbeat, along with another cd player that has the tape that says "Change Stations Now" every 30 seconds. Every so often (I wanna say 3 to 5 minutes), the tape sets everyone up to check their heart rate to make sure you're in a healthy target range. Each machine is seperated by a recovery pad that you use to keep your heart rate steady but give your muscles a quick break, and these too last for 30 seconds. Every month you'll get weighed and measured and get a printout of how you're doing. Every three months they recommend doing an Advanced Workout where one of the employees will follow you around the circuit and count the number of reps you do on each machine so you have a goal of how many you should be doing each time and trying to pass that to keep improving.
I hate regular gyms because you can't really talk to anyone and I always have trouble determing how long I should stay on a machine. With Curves, my friend and I go three times a week like they suggest and do it together so we can talk the whole way. Time really flies that way. And because the machines are resistance/hydrolics, you determine how hard you want to work that day. I really suggest giving it a try. Call your local Curves and ask them if you can come in for a workout so they can show you how each machine works and they'll tell you a lot more about it and see if it's right for you.