Original September 30, 2011:
The outsole is thermoformed rubber, cast with a square pattern inside and a bonded rubber tread.
The arch is a thin, steel strap, and is only held in place by the square pattern in the footbed.  It's not bonded.
The midsole is a thin, steel strap placed lightly into the square holes of the outsole.  On top is kraft cardstock with a thin canvas overlay.  There are 2 steel rivets holding them together.
The insole is a light foam insert which I replaced with sorbothane inserts and a polycarbonate/carbon-fiber arch. The welt is glued and holds up really well to abuse.
The vamp/upper is leather with large mesh cutouts that breathe well.
The toe should wrap over a little more, as this bonding failed on both of my shoes after a couple of years if very light-duty use.
The counter is bonded rubber which gives a good feel across the back of the heel.
The tongue is breathable, fluff filled, and well stitched.  There's a leather patch on it for rigidity.

Most of the shoe seemed to hold up well; however, the sole itself is too brittle.  I found that the outsole cracked, and on further inspection had torn across the ball of the foot, and across the arch.  The design is good, so I'd love to see a shoe like this, but with the outsole thermoformed over a sheet of kevlar.  This would hold the sole together better, and also protect against sharp objects.  Such an upgrade shouldn't be more than $10 or so retail.

Update 2013-08-01:
I've gone through two more pairs of these in just under 3 years.  The newest pair (red highlights vs yellow) not only tore out the sole, but the shoelace grommets tore out too.  Instead of punching a hole for the grommets, they cut a hole.  This leaves a big gap as the material stretches.  If the sole hadn't failed, I would have replaced the grommets.

Yes, three pairs.  While it's disappointing to have the shoes fail, the price is decent for what I get out of them.  By now, I should just purchase kevlar strips and solvent-weld them inside.  :)