I have had 2 pairs of this model in black.  I got a pair in Spring of 2011, within a year, the soles started to separate.  I ordered a second pair in early 2012 and now the same problem, the soles are starting to separate.  I like the shoes.  They do take a few days getting use to.  But the soles separate...they don't wear out, they just come apart and are definitely no longer water tight.  I wonder if the brown model is more durable...it's certainly more expensive (about $30 more).