In the last years there also have been many small, local ISPs popping up, often partly owned by the city (Stadtwerke). Some start rolling FTTH connections and finally bring germany to the internet-first-world.
Cable providers, at least Kabel Deutschland (which is the only option here where I live), are sadly no alternative, while they offer high bandwidths without volume based throttling, the traffic shaping they do at peak times and for torrent traffic is ridiculous and makes their service almost unusable.
The alternative is Kabel Deutchland. Their connection quality is pretty ok, but the throttling every evening when I get home from work is annoying as hell.
What I really miss from Helsinki is that when you order e.g. a cable connection, they'll deliver it the same day when you made the contract. It's fast and reliable. No throttling, no limits.
Although I understand why the situation is what it is. And still I'm not complaining, this connection is good enough for the most of the time.
I think O2 is also just a simple reseller of Telekom's VDSL. So apparently we have a competitive market for standard DSL up to 16Mbit (if you're very lucky, but often well under 10Mbit in practice), but not for the current generation of highspeed internet.