DVB-T is shit quality, except for the public stations - those have noticeably better quality.
Reason is, over-the-air bandwidth costs a lot of money for antenna power.
Quality via cable is stunningly better - and there, the difference between the public and private stations is just as apparent, for the most part.
(I use the hybrid stick for analog cable in Hamburg, and I get full-HD broadcast of all public stations. My provider is willy.tel)