Shot on what looks like two entire sets, Shapeshifter is a dirt cheap production and looks like it for the entire running time. In a decent movie, the budget concerns can be overlooked. With a movie like Shapeshifter, it doesn't take much to figure out that this is hardly one of those movies.
Set inside a dank, worn down prison housing around eight inmates (in three cells), one of the newest arrivals turns out to be a little more than a standard killer. Luckily, thanks to our prison system being equal opportunity, one of the inmates lets us know he's a shapeshifter. He also happens to know how to kill one, why they eat, and other general specifications about a creature that doesn't actually exist.
After the standard "this is what we're dealing with" speech, the movie becomes a substandard horror flick. Inmates and guards work together to find a way out as the man/monster combo slowly picks them off. None of this becomes interesting in the least since the creature mutilates its victims the same way each time around. Lots of intestines, legs, heads, and other organs find their way into its mouth in typical man-sized monster movie fashion.
The critter is a weak guy in a suit, filled with mangled hair, horns that constantly jiggle around as if they're rubber (the mystery may never be solved), and various editing techniques to keep it out of the viewer's sight line. Screeching with the same exact roar given to King Kong in 1976, the shapeshifter offers little of anything new to the genre.
Characters are little more than fodder like they usually are in a movie along these lines. There's a lowbrow attempt at racial tensions between inmates that's more offensive than gripping, and none of the actors here seem to be doing anything other than collecting a paycheck.