I have a bowflex and the main advantage is that the machine is relatively portable, doesn't take up too much space (but you need room for the bows to flex down and about) and won't risk your floor like a 'real' workout set (weight stack or barbells and dumbbells). However, I don't think it's worth the money.
The bowflex movements feel funny because bending the power bars is a progressive spring load - fairly light at the start and very heavy at the end of the movement.
I'm not sure if this is an advantage or disadvantage but 'real world' items don't usually have that sort of progressive resistance (e.g. that 20 lb bag of groceries feels like the the whole 20 lbs when you're getting it into the trunk of your car). A lot of current exercise recommendations focus on 'functional' capability, and that is best served by using loads that closely simulate how you would use the muscles in real life.
If you check out the bodybuilding and weightlifting forums, the most highly recommended equipment is a good bench and a full set of dumbbells, and then when you get serious add an olympic barbell and a power cage (the power cage helps you do squats without a spotter, and the squat is considered the most important whole-body exercise)
A site you might want to check out is exrx.net, read through the beginner's page, they have a lot of excellent guidelines and advice.
Bottom line? If I could do it again, I would pass on the bowflex.