i've found net radio quite mixed in terms of quality. Some I'd say are better than DAB, others are pretty poor. But the sheer volume and diversity of music available is really educational and exciting to explore - in this sense alone, it's far superior to anything DAB has to offer. If you like exploring new music, net radio's a must. Sure, it's not up to a good FM reception, but that very much depends on where you live and whether you actually like your local radio stations!
I've particularly enjoyed Sky.FM to be pretty good with a vast array of channels for each genre of music. Their channels are especially good for jazz. I found them under North America / New York. New York has literally hundred's of radio stations, but Sky must have 60 odd stations, some of which I've saved as regularly used favourites.
Sky.FM offer a "CD quality" service if you subscribe, although I'm not sure about the validity of that claim. I just use 'net radio on my AVR, so can't explore this option anyway, but the standard quality is no worse than DAB.