Pros: Body weight exercises, very flexible, effective.
Cons: Some changes and many exercises awkward, is overpriced when bought new.
I bought a used Soloflex on ebay for about $400. I have been using it for about a year now. There are definite pros and cons to this machine.
The body weight exercises are great. You can do pullups, dips, body curls, and other various exercises that you can't on most home gyms. And no, a lat station without hold downs is not the same.
The squat and deadlifts on the Soloflex are also pretty good. The Crossbow and standard Bowflex, for examaple, are terrible at these. The squat is generally accepted as the best exercise you can do, and the Soloflex does them pretty well for a machine.
You can also add real weights to the Soloflex, making it very flexible. Real weight is always better for results than bands or bows, so this is a nice feature. It is capable of handling 400 lbs of bands, plus 500 lbs of weight plates, giving it a 900 lb total limit. You'll never outgrow that.
As you would expect, a machine that can handle 900 lbs is built pretty solid. Other than the bands, There is not much that can wear out and it should basically last forever.
The floating bar, while not as good as freeweights or a cable machine, is still better than what most machines give you. For those of you who don't know, the floating bar basically means the bar is loosely attached to a single point, allowing it to "float" up and down on each side, requiring more skill to keep it even while using it, more like a barbell.
Overall it is capable of giving you a great workout. However, it is far from perfect.
While it is compact, the fly and leg attachments are quite large when not being used. You will need to plan on at least double the space you need for the basic machine. The actual "base" unit is only 4'x4' but you will need space to get around the thing too.
Some exercises are very awkward. Like getting into position under the bar to bench press. Also, the bench is too high. At 6'3", it is ok for me but my 5'4" wife cannot touch the ground in many posistions. When the leg attachment is connected, the bench is too high even for me to do anything but use the leg attachment. This means it can't just be left on all the time. Not a big deal but it is cumbersome to add and remove. Actually, we don't even use it anymore, as squats and deadlifts are better exercises anyway.
Many of the changes may be difficult for beginners or the weak, as the attachments are rather heavy. But most can be done within 30 seconds with practice, more than quick enough.
The bench is also not securely attached on the one end, it just kind of sits on top of the legs, so it doesn't have a real secure feel to it. The whole machine could also really use a stabilizer in back like the one on the front. Although it is built solid, that doesn't exactly make it stable, especially on carpet. It is not unstable, just not as good as it should be.
When in position to do pullups, the bar is over 7' tall, meaning that you won't be able to do pullups in some basements. And the dip station is too narrow.
My biggest complaint, however, is the rubber bands. I've had to buy over $70 worth of new bands already. Since I bought used, I really don't know how long they last. But they do cost about $0.50/lb to replace, which I find absolutely ridiculous for chunks of rubber. Also, the bands give very progressive resistance that just does not feel right. Of course, the Crossbow is about as bad, the Bowflex somewhat better.
It is also way overpriced. For the $1770 price of a new one, you can buy better "non-infomercial" machines such as one by BodySolid or Parabody. Or a really nice powercage and freeweight set.
I have seen great results, but I do supplement with dumbells and real cardio on off days with biking or my NordicTrack (no, the "bows" do not offer very good cardio, regardless of claims). I looked at buying a Crossbow, but found the lack of good squat, proper hold down lat or pullup station, along with the same progressive resistance of the Soloflex, just didn't meet my needs.
I'll be purchasing a powercage and freeweight set eventually. A good powercage will give me pullup and dip stations, as well as a safe place to do freeweight exercises. Best of all, it will cost under $1000 and be far superior to any all-in-one machine.
Bottom line? Soloflex does the job. With just a few minor improvements, it could be a top-notch machine. It's frustrating they don't ever improve it. I wouldn't recommend it at the new $1770 price. Around $400 for a used one can be a good deal. It really depends on your needs. I feel somewhat advanced users will appreciate the bodyweight and weight plate exercises on the Soloflex. Beginners though would probably prefer a simpler machine like the "bows". Of course, the most advanced users, or people with advanced goals, would be better off sticking to freeweights.
*****Update January 2008********
Just thought I'd come back and mention that for the past 4 years I have been using a Parabody power cage, free weights, and a Hoist bench. Cost: $1100.
I have not missed using my Soloflex one bit. Well, OK, I do miss the vertical situps, but I can do all the other body weight exercises better with my current setup. I feel freeweights have helped to give me better real world strength than the Soloflex. Moving real weight in three dimensions is much more effective in this regard than pushing a bar one direction in a fixed arc. And in my opinion, it is more enjoyable. I have had no joint problems with free weights, as you shouldn't when used correctly, and the cage provides safety. With how sturdy and solid the cage is, it is probably safer than my Soloflex.
Like many machines, Soloflex forces you into a predefined range of motion rather than your body's natural range of motion. While this generally is not a problem for novices, lifting large amounts of weight this way is not safe.
I have tried selling my Soloflex locally (city of about 175,000) for as little as $175 but have not been able to. It is difficult to sell online because it is difficult to ship, not just because of weight but because of the size of the main beam. When I bought it in 2002 UPS and FedEx would not ship it, don't know if that has changed now. The exact same machine with a vibrator attached to the frame costs almost $2000 new today. Look on ebay, resale is terrible.
I tried dusting off the Soloflex last month for fun, and let me tell you, it wasn't much fun. It may do a lot, but it really doesn't do anything very well. No grips for your hands, hard to get into position, awkward range of motion, awkward resistance, unstable bench and base. Really basic stuff. Because of this new perspective, I have removed a star from my previous rating.
Again, if Soloflex would do some simple updates on this thing it could be pretty good. But the flaws I have listed are inexcusable at $2000. There are better options out there for a lot less money. Keep in mind this thing was designed over 25 years ago, with the only basic improvements since then being a padded bench and a vibrator.
If you are short on space and can pick one up for around $200 with lightly used straps you should be able to get your money's worth out of it. Personally, I wouldn't pay more than $250. Again, it can be effective, as just about any solid workout plan using resistance can be. But like most Soloflex products, it is not worth the full asking price.
Don't just take my word for it. Go on any weightlifting forum and ask around.