For me DAB is about choice, the FM stations in the North East all sound the same to me, play the same pop songs all day long. I prefer rock/indie music. That isn't available on FM here. I could listen using mobile apps, but I drive through patches of no/poor 3G/4G signal. So I prefer DAB.
I agree, if you don't have DAB in your car it's not worth the hassle getting it installed (unless they are actually going to turn off the FM signals like they said, is that still happening?)
My DAB keeps dropping out in built up areas, mainly in Leeds, and it's not like FM where you just get a fuzzy sound for a few seconds, it just cuts out completely and randomly comes back even when stationary in traffic. It makes me think about switching back to FM, I mean the only advantage is sound quality but with road noise that isn't noticeable.