I'm a just over 6' and I find it very comfortable. Not cramped at all.I'm 5'10. I can't imagine this bike being comfortable for anyone over 6'0. However, if you are a tall guy, then you are probably use to being relatively cramped on a bike- thus you have grown accustomed to it. I hope that makes sense.
I´m only 183 cm / 6´ but sometimes I wish to sit an inch or so higher for less knee bend. So I had a crazy idea: Why not stuff a bicycle tube into the seat and blow it up. I did it today and it works like a charm. Higher and super comfy.
at 5'7' bike is perfect. my buddy who is 6'1" said on his demo ride that it felt way too small and that his back felt a little tired after the 20 mins ride. He has a 33" inseam. Don't know if it helps but the upholsterer I've used in the past to circumvent the "moto" only seat guys said he could easily stuff upholstery crap in their and make it about 1.5 or more inches taller. Of course it would be soft, so it would squish down but its better than nada...I almost feel like buying rubber membrane and making a seat shaped 'whoopie cushion' using this principal. Getting the seat at least an inch higher would feel a lot better to me. I'm only 5'9" and 30" inseam, but the bike feels tiny to me, like I'm riding someone's BMX bicycle around. That's not a bad thing since it keeps your center of gravity down, but it'd feel better to me if the seat was a bench instead of a hammock.