I'm an avid Brooks glycerin customer.  The first real running shoe I ever wore was a glycerin 10, and I knew the second I put it on my feet that I would never buy another brand.  It was very light, and extremely comfortable.  Unlike any other new running shoe I tried, the glycerin 10's felt like slippers, like they were already broken in, perfect for my feet.  Shin splints and all other usual minor pains in my legs or feet became a thing of the past.  I bought the glycerin 11's the next year, glycerin 12's the year after, and they felt just as good.  Unfortunately, I can't say the same about the glycerin 13's.<br /><br />The glycerin 13's are much stiffer with less cushioning.  There's less room for your toes also because of the now tapered toe box.  They simply feel cheap and uncomfortable, much like any other common 40 dollar running shoe you could find anywhere.<br /><br />Bottom line, if you're a glycerin fan like me, please try these on before you buy them.  They're definitely not the same as past models.