These shoes are extremely lightweight.  The cushioning is moderate, it does have a different "feel" to it than other running shoes, perhaps due to the lighter materials used for the cushioning.  The shoe has a lower drop, meaning the heel is lower to the ground than the average running shoe (6 mm drop vs 14-15 mm).  This will affect your running form if you are used to a standard shoe.  I have used them only on my shorter runs (3-6 miles).  I tend to reach more for my trusty Mizuno Wave Riders for longer runs because of the cushioning.  The shoe seems less flexible than other shoes, the mesh overlay in the upper is stiff.  This bothered me at first but is no longer an issue.  I think these will be my 5K racing shoes.