To resurrect an old thread: no one answered who had ever used the TRX, so I'll go ahead. I recently got the TRX military kit and it's worth the price. I also own a set of rings, but even these are quite hard to set up in the field. The TRX can be used anytime except on foot patrol (and who likes to break up a tab in the Nooristani mountains by doing a separate workout?).
I did wonder whether I'd feel ripped off for paying $200 for something that I know has very cheap components, but sometimes you do pay for the know-how of putting cheap components together well (E_C's problem?). I'm happy I bought the TRX thingy.
I was introduced to the TRX by a US Army cav major when we were both staying in the transient tents outside the KAIA military terminal. He attached the thing to a nearby lamp post and, voila, he was getting a full workout in. It looked awkward to transition from exercise to exercise - particularly from having your hands in the straps to having your feet in the straps - but you get used to it pretty quickly. The major had grown to love the TRX as a cav squadron commander in Logar Province and his enthusiasm for the device was quite infectious.
For once, the DVD that comes with the TRX is actually useful. It substitutes for having a trainer showing you how to do things, and it's a lot faster than looking up every position in a manual (one of the problems of Crossfit, where newbies have to look up separate videos of each exercise component). After the initial intro, I had no trouble figuring out my own workouts.