The basic idea behind the compression recovery units is to force fluid (which contain metabolic biproducts, inflammatory biochemicals, acids...toxins for lack of a better term) back into systemic circulation, allowing for the delivery of "fresh blood" and thus improving recovery. I will have to dig up the study, but there is some evidence to show the underarmor full body compression suit improved recovery following a D1 football game (or practice). This was done at UConn.
Either way, a good light cardio cool down, foam rolling, and then a contrast bath will do the same thing, for a fraction of the monetary cost.