My wife had been after me for the past few months to start doing yoga classes (but who has the time?) to help with some chronic neck and shoulder pain that I have, I saw this on Amazon as a daily deal and since it was discounted about 15% from the regular price I decided to go ahead and buy it.
Assembly was a little difficult (in fairness the manual warns you that two people should be involved, but I did it by myself), I found that actually tilting it up so that the front of the frame was lying on the ground made it much easier to put the main bolts through the two primary supports. From that point onward the assembly is pretty routine. A step that you might miss but is important is to leave some slack in all bolts until you are fully assembled, then you can tighten everything up.
I should also point out that at the premium price for this device, I was surprised that the metal parts were only painted instead of being powder coated, for the price Precor is charging they should be using the same power coated steel they use on their home Elliptical and other high dollar fitness machines.
Now, on to the use of the StretchTrainer itself... as other reviewers have mentioned, the device allows you to do many of the same deep stretches you would get on a mat, doing yoga or something similar, but it makes it much easier to do these. I don't know about others, but I tend to have a very hard time stretching properly on a mat, and there is very little motivation to crawl around on the floor doing stretches. With this machine, I can simply walk over to it and get a good pre-workout stretch in about 10 minutes. Since I am sitting on the machine I can watch a bit of TV while doing it and I'm not rolling around on the ground (sweating profusely).
I have observed less soreness since I started using this before all of my workouts. To give a specific example, if I do incline bench presses, and butterfly lifts, I am usually pretty sore for one or two days afterwards... to the point that I might have to take some muscle relaxers in addition to non steroid anti inflammatory medication. This is due to the problems with my neck. Since using this machine, I have not observed this level of soreness following a workout. In addition I notice a little less pain when seated for long periods at a chair in the office doing computer activities, so, as far as I am concerned, the machine is worth the hefty price. I saw a similar machine at a fitness store that was a non Precor model and it was $599 so the price I paid was pretty reasonable compared to the competition. In all honesty though, this is something that should probably be sold for more around the $399 price point.
Do you need this? Maybe, maybe not. There's nothing that the StretchTrainer does for you that you could not do for yourself with an exercise mat, some patience and practice. However, I feel that it does a good job of more or less goading me into stretching before every workout and the machine more or less enforces the proper posture to get a deep stretch without hurting yourself (you control the intensity of the stretch with your body weight).
Also, this is not a miracle cure for back pain. I still have back pain. However, if you are somewhat fit, are interested in staying fit, then this will probably help you as it will keep you more limber during workouts, increase your flexibility (there was a study I saw online where this was proven to increase flexibility in test subjects) and probably reduce the pain you are feeling to some degree.