Biggest shock?
Stepping into an R22 after 7000 hrs turbines. Eeewwwww....
But after the shock of wrestling with the flimsy little critter, saw that it does a pretty good job.
Worst aircraft flown?
Without doubt, the Enstrom. Shake, rattle, refuse to start when hot, can't even hold height if the turbocharger develops a problem - the piston engine by itself doesn't have any guts unless the turbo is up to speed. Yuck.