Some things to keep in mind about the theater experience.
Only a handful of theaters do film IMAX anymore. A lot of IMAX locations are just 4k DCP (Digital Cinema Package)
Most theaters in the world are digital projectors with a max resolution of 1998x1080 or 2048x858
Part of the reason these factors still exist is cost. A poorly maintained film projector with a lousy film print can ruin a movie going experience. Hollywood would sometimes release so very shitty prints. The digital projectors are much easier to maintain so the experience is often more ideal for the average movie goer.
Having said that, if a theater takes good care of their film projectors and they have a well made and well kept print, the experience can be amazing.
King of Prussia seats (center-ish and towards the back) are basically reserved out until August. Even if you want to drive out there you'll have to wait. That's how rare these projectors are lol.
15/70 is the IMAX film format, using horizontal frames, 70 mm tall and 15 perforations across, in comparison to regular 70mm (large format) film which has much smaller frames turned vertically that are ~5 perforations tall.
I'm going to make a 3 hour drive to my closest real IMAX. Haven't had the pleasure to even see a mini IMAX film and am a fan of Nolan's work so I'll make the time.