A fun concept, but poorly executed. Except for the fairly good makeup effects, there's really not much to it. There are obvious problems; for example, after taking what seems to be weeks and weeks to get from fat to normal size, the main character seems to go from normal size to deathly thin in days... and once he's deathly thin he stays pretty much equally deathly thin for what seems to be a long time.
In any case, the movie has far worse problems than that--the cinematography is decidedly low-budget-TV-show quality and most of all the acting is pretty awful all around. Robert John Burke seems to always be trying for some kind of weird snarling Charlton Heston impersonation and is literally painful to watch... the only scary thing is that Lucinda Jenney and Kari Wuhrer are both even worse.
The only reason why I'm giving this movie as high as I am is that once the movie enters its last 1/3 or so and Joe Mantegna's character takes over, the movie develops a fun, campy 'cheesefest slaughterhouse' feel, and the gangster's crazy schemes for tormenting the totally obnoxious gypsies are somewhat fun to watch. The ending, if predictable, is also nicely mean. Avoid unless you're a King-o-Phile or are REALLY psyched up at the idea of the voice of Fat Tony from the Simpsons terrorizing a gypsy camp.