I actually have a DAB radio in my Mini. It's pretty expensive as a factory-fitted option new, but it was one of the features I looked for on Autotrader when I was searching for a used vehicle.
Pros:
I listen to 5Live and the improvement over AM is vast - and I get Sports Extra.
R3 reception is terrible locally, so although it might not be the last word in hi-fi, it's great to have clarity and no hiss or whistling.
I can also listen to to 6 Music and other digital stations.
Leicester Tigers commentaries are normally only on Radio Leicester DAB (football on FM!)
Cons:
The radio interface is horrible and there aren't even any proper instructions. I had to look on the internet and find a Mini forum! The main problem comes when you try to switch between multiplexes. Unlike that being done for you (as in Pure radios), you have to do it yourself before you can get to another set of stations. The only solution is to grit your teeth and do it once, saving stations into the presets. Then, if you only use the presets, you don't have a problem!
In practice, I hardly ever use anything other than DAB, although the radio has AM and FM too. There are hardly any drop-outs and they occur in strange places like the roundabout coming out of Tesco for about 20 metres, so I can live with that!!!