Mine has been very reliable (1990 model). If he's specifically after the SX, make sure it is an SX. I read a few years ago that some have been trying to pass off others as an SX. Check for all the individual gauges on the dash - temp, oil, battery. Also the SX is the 100kW not 86kW (?), so check for that and the support across the engine bay. The first thing you'll notice though is the spoiler on the back.
It hasn't had any major problems. The rear springs don't like having a tow bar permanently connected. Has a little trouble going to 2nd after high revs. That's about it.