I have 2 Harmony mats (3/16" and the travel), and I love them. They have wonderful traction, and the cushion is pretty nice too ~ even in the travel mat. I'm so spoiled by these two features, I refuse to pull out my plastic $20 mat anymore, even for a quick 10 minutes.
The mat will have a strong rubber smell for a few weeks, but that fades. The thicker mat is heavier than a typical yoga mat, so you'll notice the weight difference immediately. If the weight bugs you, the thinner travel mat is a good choice.
Also, because of its composition, I discovered it doesn't slide in and out of a yoga mat bag too easily.
Well,
my yoga bags anyway (I made my own out of cotton fabric). I solved that by buying an inexpensive yoga mat strap at Target.
It shows dirt a little easier than the less porous plastic mat. I wash mine with antibacterial wipes, but I have yet to dunk it in the tub. I believe it comes with washing instructions. One guy at Yoga Journal says he takes his into the shower with him.
I've had my older one for 2.5 years, and the travel for a year. I don't haul them back and forth to class anymore, but both stood up to class time up until roughly 8 months ago when I stopped practicing outside the home.
Yoga Site has decent prices:
http://www.yogasite.com/yoga_store/ym.html
I have heard some complaints about loss of traction by those who sweat profusely during practice. I haven't had this problem, but I 1) keep a big towel handy and 2) don't drip sweat when I practice.