I just wanted to add my experience here. I bought a Tria back in 2010 and used it for over year. It's a real laser, and it permanently reduced my hair, but it has limitations.
It's battery powered, so you have 15 - 20 minutes to treat a hand-print-sized area. Then you have to wait for it to recharge (1.5 - 2 hours if I remember). And the "pulse width" is very long, so the laser has to be moved slower than a commercial laser. So you have to be very patient, and just don't expect to treat large areas with it (like a whole leg).
It's a very weak laser. I always used the highest setting, but compared to my commercial laser treatments (Alexandrite and Diode mostly), it took many, many more "zaps" with the Tria to achieve a noticeable result. Even after 6 - 8 rounds of treatment, the Tria mainly lightened and softened hair (where as commercial lasers had finished destroying the hair altogether, probably because they can move up to higher "fluence" settings).
It's super painful (at the max setting). With a commercial laser, the pulse width (the time the laser is "on") is really short, so you can "grin and bear" the snap-like pain and it's done. With the Tria, its' soooo slow (like a constant burning sensation, rather than a snap). I thought it was much more painful overall. And that was with using EMLA.
So overall, I don't recommend it, unless you are treating very small areas (like the back of your hand or knees) or the odd stray hairs that were missed by commercial laser treatments.