I own a Zxi for the past 6 months. Have gone 2, 000 km and use it regularly for city drives( offices) and have taken it to long distances(200K+) journey as well. Well I always look at it as a normal 5 seater car, but can use the extra space to accommodate people when required.
The last seat is reserved for kids when we go on family picnics. They dont complain and others are happy as they have their own space instead of jumping / screaming on top of everyone else :)
I wish it was a bit longer but then I have parking issues, so the length is perfect (same as a normal sedan). Easy to drive in the city and totally under control on the expressway(had driven at 135km) without rattling the interiors.
Would have liked better suspension though.