The NB Zip is a sturdy shoe.  It does not feel soft and cushy like the 992.  Instead, they feel solid and responsive.  I ordered a pair of the original 8505 Zips when they first came out.  That shoe is okay, but it can begin to feel stiff on long runs.  The newer model 8509 has some improvements in the outsole that make it more flexible and less stiff.  The Zip is a good durable shoe that will wear for a long time.  If you're looking for pure comfort, choose something with more traditional cushioning.  If you like solid and responsive, then this shoe is for you.