Pretty good. Moranis is fun and the kids do a good job. Special effects are top notch.
Leonard Maltin/Plot synopsis:
Cute comedy-fantasy about a quartet of kids who accidentally trigger Moranis's experimental ray gun and find themselves reduced to microscopic size--and stranded across the yard from their home. Enjoyable family fare, with engaging special effects (by such whizzes as Phil Tippett and David Allen). Followed by HONEY, I BLEW UP THE KID and later, a TV series.