I got into the idea of barefoot running about 5 yrs ago, after having to deal with shinsplints/plantar fasciitis/ITB, on both sides.  A recreational bodybuilder, I carried a little extra weight for my height, and this may or may not have contributed to overpronating (as described by a sports medicine physician), moldable arches (as diagnosed by an orthopedist), and flat feet (as diagnosed by a rheumatologist).  Rather than pursue arches, as more "supportive" shoes only seemed to provide temporary relief, I decided to go the complete opposite direction after doing some research.

After 5 yrs (1yr on the Nike Free 5.0's and 4 more after that on the Nike Free 3.0's), I have been injury free.  Running for an easy 60min on a trail, or a hard 10minutes on a track, the Nike Free 3.0's never failed me.  Ordering my most recent pair of Frees, Nike told me they were discontinuing the 3.0's.  This shoe is really the only comparable product out there.  After 2 weeks here is my take:

What I like:
This would be the Nike 1.0.  After running a fairly hard 30min on a dirt/gravel trail (after a week of shorter/easier runs), I was pleased to find that, having trained in the 3.0's my gait needed no retraining.  Interestingly, like another reviewer here, I did find that my calves were significantly more sore after running in this shoe.  Presumably, this was energy being absorbed into the muscle, and not into the joint, as I had no joint soreness at all.  From a bodybuilder's perspective, these are great to work out in.  I was worried about the pressure on the toes, but even on heavy leg presses, there is no stress on the toes (something that was present on the Free's). I understand why Arnold worked out barefoot.

What I don't like:
These shoes take longer than a normal shoe to put on.  There is improvement with practice, but still, I don't think that you can just "throw them on," and bolt out of the locker room, or your front door.  Particularly, because I recommend training in them with the toed socks which seem to prevent hot spots, and these socks really take about a minute to put on.  The shoes, after some practice, can be done in about 30-40seconds.
Also, when running on rocks (on a trail for example), you do feel them.  Finally, unlike the Nike 3.0's, you really don't have the option of a heel strike, and they are brutal when running on concrete.

Bottom Line:
As of right now, I think I'll probably keep both. Train in the KSO's, but "race" in the Free's, especially when terrain might be hard.  Probably my lifting shoe of choice.
They get 5 stars because they do what they say. I'll be sure to update if they break my 5yr injury free running streak.