I've had one on location for three days. My thoughts:
The Ghostbusters theme does not get stuck in my head, but the one that does is the Spooked Librarian music...really awesome and unique as far as pinball music.
Several players have complained that I need to "fix the flipper angles". They're aligned with the pilot holes in the playfield. The flippers are pretty flat even when all the way extended - but that's how most Trudeau games are.
The art and sound package is awesome. Universally praised by everyone who has played it. The Storage Facility Multiball start is cool.
Playfield layout feels very fresh and original. I'm not sure I really like how the right ramp works, but in not knowing the code, I've been mostly ignoring it. I've seen balls catch a few times on the switches that measure how far up the ramp your shot went.
I don't have a good grasp on the rules, but it feels like there is a lot to do and scores range wildly in modes depending on how you play them. Like Game of Thrones, it's going to really reward you for a deep understanding of how to progress through the game.
Slimer wasn't registering consistently at all. I made a not-quite-sure-what-I-actually-did adjustment and it seems better now. The left spinner was stuck horizontal, but bending the bracket fixed that. I've had a few people complain that auto-plunge is on, but it's not, and I suspect that there are bugs in the code. (For example when you boot the game, the first ball you play seems to always be auto-plunged).
The biggest bummer I've seen is balls jumping the inlane/outlane ball guide. It has probably happened in 10% of the games I've played. Also, sometimes you get STDM out of the left exit of the pops...which is uncommon in modern Sterns with how they're typically confining the pops to a separate area with only one source of exit.
Overall, this is the best first impression I've had of a modern Stern game. One player said: "Meh...it's boring", but everyone else that has played it has *really* liked it. Can't wait to figure out how to actually play it!