I wore these shoes for the first time yesterday and was really very impressed with them.  I had to sprint across a busy highway at one point and felt like I was bouncing along.  I am used to the negative heel and wore them for about 7 hours.  I would suggest that you go slowly if you are wearing this type of shoe for the first time.  Another thing I noticed was the stability which is lacking in a lot of this type shoe.  The sole is not so  high and arched that it is unstable.