Ordered a Pietra earlier in the summer and fell head over heels in love with the comfort, fit and durability. Wore them for days & miles right out of the package.  Thinking all Fitflops all have the same bottom & fit, I ordered the Walkstar 3... Wore for 2 days, only to get blisters and  an all around uncomfortable shoe ... The base was bigger than the Pietra and it's ill fitting. I'll stick to the Pietra ...  Overall love it - just wish there was consistency across the brand !