I looooved the Brooks pureflow 3.  I was hoping the pureflow 5 shoe would be more of the same but in a much more awesome pink and black color.  The shoe retains the lightweight feel, snug toe box, and comforting all over gentle squeeze that the I loved about the generation 3.  However, I had to return these shoes because the top, back part of the shoe where it goes up on your Achilles tendon is too tall and has a sharp support piece that digs in.  I wanted to love these shoes so much because everywhere else fit great and I love the pink color, but immediately after putting them on and walking in my kitchen I already had raw red spots on my heel tendon areas.  Why did they make the heel part so high?  Everything else about this shoe was great, but they are unwearable.  To be clear, this model of shoe is intended to fit snug on your feet.  That doesn't mean you should order a different size than you would normally wear, that means the shoe is designed for a more comforting all over hug feel rather than the roomy sloppy sloshy feel of most running shoes.  If you don't like the snug fit, then this line of shoes is not for you.  For me, having my foot in a shoe that fits so close allows me to have great response between bending my foot and the motion of the shoe.  The pureflow shoes reminded me of ballet shoes in the sense of lightweight flexibility, but alas the pureflow 5 is terrible because of the heel