here's the thing about the blowflex. i don't own one because i don't have the space for it, but if i did, i might buy one.
i've used one at my friends house a couple of times for a complete chest workout and i was sore the next day, even though i was regularly working out at the time, and usually that doesn't happen (the getting sore part).
bench pressing feels pretty different because you'll be shaking a lot, using a lot of strength to keep your arms stable.
the secret to success in using the blowflex from what my friend told me is not to lift like you lift free weights, which is drop on as much weight as you can, and repeat the reps as quickly as possible for the sake of pumping out reps.
with the bowflex, you might have to lower the weight some, and then use 4 secs in both lifting and lowering phases. i've tried lifting fast and can do twice the reps as lifting 4 second reps, but it wasn't as effective.
i would definitely say taht if you get a bowflex, supplement with free weights as well. one plus of the bowflex is that you dont' have to deal with dangerously heavy plates/weights and can work out with a spotter.
but there are just certain things you can do better/easier and more effectively with free weights. bowflex is good for bench pressing and lats/rows since most home gyms don't have those attachments. and since the bowflex is a bench, you can use that bench to lift free weights as well.
to those that say a gym membership provides a better workout, i won't disagree but lets factor in cost.
$30-50/month versus $600-800 for the life of the machine, there's no comparison. lets just call it $40 a month. @ $40/mo., your membership will last you a little over a year and a half when compared to the cost of owning a machine. if you treat any machine right, it will last well over a decade.
plus, it gets worse if you don't go to the gym. many people get lazy and can't stay devoted to go to the gym regularly. i have friends who signed up with me, go 3x a week for the first month, slowly tapers off until they completely stop going. its even easier to skip out if you're far away from the gym.
the convenience of having the gym in your home can go a long way. it's always available, privacy, cleanliness, etc.
weigh the pros and cons based on availability, cost, distance, convenience, time, etc.
one pro of going to the gym, the hot chicks on the ellipticals