As a car for two the Mini is fine. I've got a Cooper D that's just over 18months old and it's a second family car with the other being a small people carrier type.
There isn't much room in them but with a bike carrier on the Mini towbar I can get our family of 4 out with the bikes on a nice day (with minimal extras beyond Camlebacks and helmets).
It is good fun to drive, not super fast but it feels nippy and is certainly fast enough to get a ticket. It's got 17 inch wheels and fairly low profile tyres which seem to help make he ride quite firm, I like that though. My last car had 18 inch lower profile run flats, I liked that too.
The curvy shape does seem to result in the reverse Tardis affect mentioned before but as I say for a second car or if there aren't many if you to transport it's fine.
I have been a bit disappointed with the feel of the interior but then the car before was a BMW which despite what some say about being bland blah blah was very well put together compared to any other car I've had.
Test drives are the key. It won't take very long for you and your wife to decide whether it's right for you both or not.