A few minutes ago, the top voted questions were about whether he uses Internet Explorer, Bing, etc. It is a bit disappointing to see such inane questions getting upvoted to visibility. All I can think of about that commenter is: You have one question to ask one of the greatest businessmen and philanthropists of our time, and all you can think of is some re-hashed 10 year old joke? I think in general, r/all is pretty stupid. However, many other subject-specific sub-reddits are awesome!
I find it depends on the subreddit. It's like HN, if there's a consistent effort at civility and on-topic discussion in a particular community, then it can be ok. All of the default subreddits are a disaster for discussion, some of the smaller niche ones are ok.
That's like the elevator pitch for Reddit comments. It really just depends on what you find humorous I guess.