I really like games with a third and maybe even fourth flipper. I believe the last 3 flipper pro game was ST. Having more flippers adds more shots and more interesting playfield layout.
I also wish Stern did a better job with labeling inserts and callouts to better explain how to play. I guess deep code is what people want but it just seems so difficult to learn how to play some of their games when you only get a chance to play once in a while. In general, I just don't get why there are not 100's of different callouts in games. That has to be the easiest thing to code and memory storage is cheap. I also don't see why Stern cannot have an option on their new larger, color displays to explain basic rules like how to get to multiball and how to play out modes. Maybe even have a tutorial mode that cuts out the music and goes into detail what to shoot for.
Art and general presentation is another thing I don't understand. It seems like every games should have top notch art, plastics, and such. That should be the easiest thing to do. I suppose there are licensing restraints but still doesn't explain why some Stern games look pretty bad and some look awesome. All arcade games should have an amazing look to them that draw people in to play. Home buyers will also line up to buy games based purely on pictures. Games that don't look good have to depend on gameplay to sell but not many people get a chance to play these games on location or at shows.