I think the biggest failure of Buzz is how confusing it is. I think this is one of the most misunderstood products that has ever been launched. I honestly believe about 90% of the complaints we've seen are misunderstandings of how Buzz works, and how the information that it sets up looks to other people.

For example, in my experience the autofollow doesn't reveal nearly as much information as some people expect:

1) It doesn't reveal anything if the person you autofollowed doesn't have a public google profile.

2) It never reveals the email address to anyone who already didn't know it

3) It doesn't really reveal on what level you have any contact with the person, because an outside observer has no idea whether you autofollowed this person or chose to follow them. For example, about 50% of the people I'm following I've never emailed before (and I still don't know their email address even though I've communicated with them through Buzz now).

There are some privacy issues with Buzz, but more than anything its biggest failure is being confusing.