Purchased July 2012 and worn almost everyday in the garden, yard work and on the boat.  No problems yet and get even more comfortable. Now they can be slipped on.  OK with or without thin socks but a little more comfortable with socks.  They will wear out one day but will buy same shoes every time.

UPDATED: May 26, 2013.

Almost one year of almost daily wear mostly outside in the garden or other activities outside (painting and minor construction). This is how these Muck garden shoes have worn:

1.  Still no sign of cracking or splitting anywhere.
2.  The rear part of the heel is showing signs of wear and eventually a hole. After the hole wears thru they will no longer be waterproof. If I had only used the shoes for the garden I'm sure they would last 1 1/2 years.

I consider this acceptable considering all the wear I put on them.  I have upgraded and ordered a different Muck shoe from Amazon.