I have a DAB radio in my Mini, largely because I listen to 5Live all the time! It does cut out occasionally, but reception is generally crystal clear. The SQ on MW in our family car is so bad my OH often asks for it to be switched off!
The most important things to do are:
a) Decide whether the stations you want to listen to warrant DAB;
b) Check the DAB reception in your area. Where I live, it's fine - others won't be so lucky.