I love mine. Great fun to drive on country rodes, decent ride quality around town and it's reasonably practical. Wish I'd had the cash and buy im from Mrs to go for a punchier engine but we were really looking to buy as new a car as we could afford. The 118i in sports mode is still about as much fun as I reasonably need in a small car.
Beamers don't seem to be the most reliable - common issues for 1's are: the bushings in the wishbones going (I had to replace mine - not too pricey but a pain for 5 year old car with 36k on it). Signs to look for is any knocking sound on braking around town and a judder over 60mph.
Steering rack is a weak point too. Watch out for any rattles when driving over rough surfaces.
The interiors of the older ones are pretty rubbish and cramped, but the newer 2014+ is much better finished. On the flip -I've heard the engines in the earlier models are better.