I regularly incorporate TRX into my training. I don't do exclusive TRX routines, but using it for a variety of exercises for back, abs and legs. It's a very versatile, well made product.
For instance, the beginning of my workout called for the following yesterday:
10 sets non stop of:
10 pull up
10 jumping jacks
20 squats
20 lunges.
I can't do 100 pullups in that scheme, so I incorporated TRX into it, changing the angles as my back got fatigued. I also use it for dragging weight sleds, sandbags and stuff like that.
It's pricey, and the reality is you could make a suspension trainer with chains and pvc pipe from home depot of about 1/4 the cost. But's it's very well made, versatile and portable, so I find it worth the $$