My friend owns a 95 318ti and no problems in specific, just keep your eyes out for the normal stuff like everyone else suggested.
As for the 4 vs 6 dispute, I bought a 318i for two reasons. First off it would cost me an extra $3000-8000 CND in my area for a 325. Second it would cost me an extra $1200 CND a year on insurance for the 325. Another reason, not one of mine, would be gas milage. So there are reasons to go with a 4 instead of a 6 for some people. The 318 is still a very good car and drives very tight.
Migey