Here’s a short interview with the guy who designed a number of my favorite pinball machines, like Addams Family and Fun House. A worthy read about he design philosophy of pinball, and the current state (or lack thereof) of the pinball market.
Every designer has differing goals for the “feel” of the game. Usually these goals are a result of the kinds of games the designers like personally.
Things to consider are, in no particular order:
1) Middle shots are easier for beginners.
2) How to mix stop and go shots with nice return flow shots.
3) How fast is the overall game? Very fast games are very difficult for beginners.
4) When a shot is missed, what happens to the ball? Is it a bad, clunky thing? Does the ball come back in my face?
5) Are these shots just “there,? or do they represent something from the theme?