I've had my K12 diesel ('25' limited edition) for coming up to 3 years. I've had zero problems with it and it's done 46000 miles.
It's nippy (it's the 82 or 86 bhp version - I think the older versions are only 65 but are easily remapped up to 82 - they share the Renault Clio engine), does about 60mpg and I drive it quite hard.
Cheap to insure and tax. It also has a reasonable amount of room in boot and cabin (I have two little kids and associated luggage and there's plenty of space).
For what I bought it for - doing lot's of trouble free miles cheaply and not being dog slow it's been perfect.
However, coming from a background of hot hatches - Saxo VTS and Clio 182 - one thing it is not is exciting.
Overall I'm very happy with mine though. Hope that helps.