the 147 is a car you just feel good in.
You can feel you've got a cooler car that almost everyone else, OK maybe the Golf GTI is faster, but it's just not as good looking or cool. That kind of thing really. It's zippy, fun and feels like it has a personality.
If it goes wrong, it can be expensive to fix, but remember that you take your chances with any car you buy. If you want a boring, reliable car, you can buy a Toyota or Honda, but if you want something that you'll feel great driving EVERY day, go the 147.
Of course as others say, just ensure it's been well serviced, and make sure you can afford to pay IF anything goes wrong. Look after it, and it'll reward you by being an exciting and fun place to be.
I know it sounds snobby (or whatever), but I drive it, see a BMW, Audi, VW or Mercedes, and just feel sorry for them!! I might not try and drag some of them off at the lights though, but I feel confident that I've got a good looking car that doesn't have to try and prove it (or it's owner) is cool, it just is!!
I've got serious respect for the really fast cars of this world (M3, M5, AMG 55, RS4 and so on), but I'd still feel 'cooler' in my 147!!