I bought these shoes the start of April, 2010 and have routinely put between 30-50 miles per week on them.  I walk at least 5-6 days per week.  The exterior of both shoes show little wear including the sole which still has plenty of tread.  I'm replacing them the start of Sept, 2010 because I have worn holes in the interior lining of both heels.  I wear a size 11 4E and find these shoes to fit perfectly.  They have given me good support and have not exacerbated my Plantar fasciitis in my right heel.  I have found the perfect insert for use in New Balance shoes; Spenco Polysport Cross Trainer inserts.  I have not felt any pain in the last two years and use these inserts in all my shoes.  I was unable to purchase this model again and bought the NB646.  At first glance, the 646 is fairly close to the 645 so I'm hoping that I will get the same performance.