Got a EZ3 USX(same as above) for my fiance and, with just over 40 miles on it, the only real problem is that it seems no one tightened down the bolts. We've lost one of the bolts that hold the seat-adjust 'rods' on the seat and the screw that holds the wire that the chain's plastic tube are connected to(that got confusing, huh), and I got to a few other bolts before they jiggled anough to come all the way out.
Other than that, the trike has been astounding.
I would just suggest buying it from a GREAT LBS and check all the nuts and bolts before every other ride.