The radar system would have fit into a half a garbage can stuck on top of a hummer. Of course, the display portion would be in the crew compartment.
Defense Update shows an artist's rendition of the system in something the size of a small semi (
http://www.defense-update.com/news/MTHEL.htm). The test system pic I saw looks signifigantly smaller, but did not show the supporting equipment (power/control/cooling).
More crap to cart around than a patriot battery, but nicer to have if you need to protect a large troop concentration or similar fixed-location target (airfield, hospital, schoolhouse).