Anecdotally, I found that within my niche, Facebook was much more effective than Twitter. A subculture was associated with my niche and Twitter was home of the impossible-to-please elitists, who really just wanted to live in their own vacuum chamber and lashed out at practically anyone who was trying to hold a real discussion with them. Facebook had a much better response.

There's just something about Twitter that makes it even more hostile than your typical online forum. Maybe it's because it's so easy to isolate a tweet external to its context and get people worked into a lather over it, maybe it's that people are forced to truncate their thoughts such that they can't possibly add all the expected niceties and disclaimers and thus inevitably offend someone whenever they make any substantive statement, or maybe it's something else.

Whatever it is, Twitter is usually not a nice place. If I were primarily interested in product updates, I would probably follow the company on Facebook (the layman's feed reader).