The most noticeable thing I found when flying an early one was the effect of the full span ailerons.
At low speed they felt less than effective especially if partial droop was selected. In the criuse at about 75 - 80 Kts there was considerable adverse yaw too.
If one looks at another aircraft that may have unfairly attracted crticism (the Europa) they are both aircraft with handling characterics on takeoff and landing very different to the average club trainer.
The PFA and Europa Kits did a lot to coach inexperienced pilots and the accident rate fell.
Design mods to the later Kitfox marks have improved the breed and I believe that a pilot with aptitude and the correct introduction would find it an enjoyble a/c.
I would be wary of an early Mk1 or 2 though unless the wing has been upgraded.
Sir George Cayley