I really like Matt and Nat, but I think they're becoming really overpriced for a faux leather bag. I bought an awesome messenger bag from them a few years ago to use for school (it looked like an envelope) and I thought it was a bit steep at $100. But it lasted really well (although the color rubbed off on my good coat....). But I can't really justify spending $200+ on a fake leather bag, when I can get a real leather one for the same price.
But if you don't believe in wearing leather, then they're a great idea!