This is my 3rd or 4th pair of Gel-Nimbus 16's.  They're the best running shoe I have ever owned.  There was no break in period & I can comfortably wear them all day.  I tried to buy the Gel-Nimbus 17 with no luck....weird fit, got blisters, bought another size down & they seriously pinched side of foot.  Decided to go back & order 2 pairs of the old model as they fit my foot much better.  As with most running shoes, I had to size up from my normal shoe size but, I knew that prior to ordering since I've bought them before.