The critical distinction for most viewers dissatisfied with the newer,
smaller IMAX theaters is between theaters originally designed and built as
IMAX theaters, and retrofitted 35mm multiplex screens. In general GT and
SR theaters have screens that are much larger and seating areas that give
a much more immersive field of view to all visitors. Most MPX and Digital
theaters have smaller screens and seating areas that are deeper than the
width of the screen, so that the average field of view is narrower, and
therefore less immersive.
See also our articles on immersiveness here
and here.