I have yet to really feel any hesitation like you guys are talking about. (I have an auto) But I have experienced some shifting hesitation, like the car will be 'coasting' in 3rd and I'll lightly step on the gas to accelerate a little bit and the engine will rev up (still in 3rd) and then kinda 'bang' into gear (still 3rd) and then accelerate (without ever leaving third). This will happen, and I'll think "why didn't it just pop into 2nd to get up to speed?"
To me it feels like trying to accelerate from a stop with a manual in 2nd or 3rd gear...where you slip the clutch (alot) until you've got enough speed not fully engage it and not stall.
Does that make sense?