Was a bit skeptical upon purchasing vehicle. The two American vehicles I owned previous were junk, including a Ford Taurus. Bought for the straight six motor. Proved to be a very reliable vehicle. I drove it only sporadically because it was my 2nd vehicle. Started up everytime, even during the coldest New England mornings. I replaced the battery and oil pan during the time I owned it (both were pretty old). Was just about as reliable as my '93 Honda Civic. I'm kicking myself for selling it, I would buy another in a heartbeat.
Reliability, the solid feel of it (nice heavy metal thud when I closed the door), dual gas tanks. Horsepower suited my needs just fine, as I never did any heavy towing.
Gas mileage, But I've heard the the 300ci engine block was heavy anyway. Other than that, I don't think I would change a thing.