I've had one for several years and used it for some things before joining a gym. If it's your only option, it's not a bad one. But you should go in knowing that it's not real weight resistance. Since the resistance is based on bands that bend as you complete the motion, the resistance is not constant as it would be with free weights, weight machines or circuit trainers.
Take the lat pulldown, for example. For the first 25% of the motion the resistance is also at 25%, then 50% at the halfway point, etc. That's not going to help you like having 100% resistance throughout the full range of the motion will. Also, the Bowflex is totally useless for some major things like squats and deadlifts.
Join the Y or, better yet, a good gym. You will have more weight training options there than you'll ever get with a Bowflex.