I tried the bistro crops last year (the cotton ones, not the new wool ones) and the fit was rubbish on me - baggy knees, odd length and flarey round the ankles like I was wearing trousers too short for me...but for some reason I ordered the Petite version this season, and they fit PERFECTLY. They are literally my perfect Audrey Hepburn trousers. I'm 5'5", so not technically petite, but they're about the same length on me as they are on the model, so not too short. And I don't have skinny thighs or a particularly small bum, so no idea why the petites fit better.
Now I have to decide whether to get another colour (just got the black ones for now...)
Just thought I'd mention it in case anyone had a similar problem to me with the regular length ones :)