commercial pressures and DAB reserve badwidth
there are to my knowledge only 7 frequencies (ensembles - 11B - 11C - 11D - 12A - 12B - 12C - 12D) used for DAB in the UK right now, and they are transmitted at low power because of potential interference with old TV sets. - so the signal quality should be improving with time.
There are 31 unused frequencies, or 180 new stations available.
However, the costs of running a station, just what you are charged for the airtime, electricity, distribution costs etc. mean that it is not economic for commercial radio.
Technically though, DAB+ with its new codec, and the many additional services it can support, is a very good standard, it operates flawlessly at 10dB signal-to-noise (7.5dB in theory).
It also allows each frequency to be used for countrywide coverage, rather than the 4 or 5 frequencies necessary for one station to achieve national FM coverage. Its very spectrum-efficient, and for that reason is still the best candidate for eventual German adoption.
the problem is that commercial radio is supported by adverts, and these are "crap" - even in Richard Branson's own words - they're intrusive, moronic, repetitive, loud, irrelevant and boring. Well, for the most part anyway.
In a world where high-quality internet radio is available, with no adverts, or foreign adverts, commercial radio (as it is today) will fail, it has been out-competed.
This should not be seen as a failure of the DAB means-of-supply, but of the content provider's business model. - and this is the real message from Germany, commercial radio as a business cannot afford investment right now.
The american answer is to provide an advert-free premium service, though this is in big trouble, and may not see the year out. DAB can support encrypted channels, but these will compete with "free" in the home, and soon, "almost free" in the car.
I don't have an answer, maybe we wait for commercial radio to die, and then use the bandwidth to freely broadcast the top 50 internet stations.
Maybe commercial radio can re-invent itself as something more people can stand listening to?