Democracy in general is slow, inefficient, and often leads to corruption in it's representative variant if not kept in check.

Autocracy while fast, succeeds or fails on the person with the most power, and often leads to nepotism and nonsensical decision making depending on how far detached from reality the leader(s) are. Also, the power plays for people in the upper-middle positions seems to be more important than actually doing their jobs.

On the topic of direct democracy:
One thing I really liked regarding this topic came from Mass Effect from all places. The Asari had a direct e-democracy governing their decisions. That's something I'd be intrigued to see implemented in the real world, since we do have the technology to achieve it. It would probably be a clusterfuck, but at least we'd see how it works out.
I don't really think it'd be affected by group think that much, since that phenomenon mostly occurs in live crowds. You could think about issues in the comfort of your own home, and just vote however you feel like.
There probably would be parties similar to current democratic ones, but I doubt that they could reach that wide of an audience with proper legislation implemented (can't pay people to vote with you, etc).