As a consumer, I think I should oppose Zillow. They seem to just take public data, present it nicely, and slather it with advertisements. Real estate agents play the same heavy-handed role they always have, except now they have to give some of their profits to Zillow else lose visibility to their competitors.
I'm more excited about Redfin. Redfin makes shopping for a home closer to the self-service experience it should be, with agents dealing in higher volume with lower margins playing a lighter role. Unlike Zillow, Redfin seems to make that market more efficient, and I think that's the bigger opportunity for capitalization.