One more review edit. The others are still listed below:

Okay so PMI sold me the new version with the sliders at wholesale price. It does everything the old version did, but it seems to lack the failure mode of the old version. four stars.

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{Okay, after several years of use, I need to radically change my review. I'll leave the old one below for posterity}

I used the first generation device, before the brass sliders were added. My experience was extremely good at first, but then the device completely failed, and the company refused to do anything for me. I felt as though I was an unwilling beta tester. Their new product may or may not be better than the old one - I'm not willing to shell out more cash at this point. Here was the problem:

The moving bar wears away metal on the frame, up to the position where it typically stops (the point where it pinches the rope). Think of that worn part as a valley. At the end of that valley is a, well a sort of terminal morain, where the metal not only is at its original elevation, but it has kind of been pushed up to form a slight ridge. This "morain" acts as a block to the bar pinching further down, right at the point where the bar should be hitting the rope. As time goes by, the ridge takes more and more of the force, until I have to sand it down, or the bar literally will not move over the ridge at all in normal operation. In addition both the bar and the body get quite rough, and the friction between them increases dramatically over the entire range of motion.

If I were to use my TRE, right now, without doing another round of sanding, I would get *way* less friction than I do from my standard ATC (which is what I went back to for doubles). To the point where it is quite sketchy to rappel. Good concept, poor execution.

I give the device a 2/5

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Old review (rated 5/5)
For trad climbing on double ropes, this device is clearly the best.

Several features:

1 - The harder the fall, the more the device locks up. According to their website, this has an upper limit of about 3kN, at which point it maintains a fairly constant force until the fall is stopped. This acts as a limiter on the force your gear feels.

2 - In rappel mode, it locks off completely. At least in my experience, when I take my hand off the device, I stop moving. This is *very* handy for all the stuff you may have to do on the way down on a rap. Of course you would tie a backup knot, just in case.

3 - For bringing up two seconds simultaneously directly on the anchor, it is a superior device.

Downsides:

1 - Too much friction when using ropes over around 10.5, or very fuzzy 10.5 ropes.

2 - After holding a fall, it may lock off completely at bodyweight, or it may creep, depending on the rope. Don't expect the device to work hands-free, *even after it has locked down*.

This is not a good device for a complete beginner.

Took me a while to finally figure it out. When it did click, I cant say anyhting less than spectacular. This thing is no grigri, and does not work like an ATC at all, despite what some have said. I would give it a 5 but for the multitude of ways to incorrectly use it. But, used properly, it does everything very very well. It doens't lock automatically like a grigri, but will lock itself off as long as youve got the brake end of the rope properly secured in your hand(s) If there is enough weight on the rope after it locks up, you can let go with your brake hand, but only for a very short time (to, say, tie it off). it the belay losens the least little bit while its locked off, it will completely release. Better to not let go at all if you can avoid it.

The best system for experienced climbers, definitely. not so good for newbies, can get confused and pull the lever instead of the brake, just as with a gri gri. The rope brake is a bit dinamical, which gives the rope extra life. Great product for my opinion.

might take some time for getting used to, but then its really a nice device to have.
You definitly need to have some knowledge, to be able to use all its advantages, like rappelling, belaying and ascending in the best way.
Not meant to be used as an "hands off"/automatic device!