Bought a pair of these to replace my now-dead hi-tecs. I have fairly bad posture, and found that the barefoot training program really helped. I chose these as I'm taking up running, and normally land forefoot/midfoot anyway (which doesn't really work in normal trainers). I wear them to work, and after spending two days on my feet in them (including a 9-hour shift) I felt only a little bit of an ache around the calves - although not totally unpleasant.
Although not waterproof, these shoes breathe REALLY well. They feel like slippers when walking around, and generally just make me happy.
The only thing I've noticed is that they really "want" to run. It's great walking around in them, but the shoes naturally fall as if running, and invite the next step - clearly not a bad thing!
If these fit you, buy them without hesitation!