I have never met Ulrich, but have exchanged emails with him over time since oooh 1994 I think. He can be a curt SOB in how he writes, but it is a tendency he shares with Al Viro and some others. He has the ability to laser in problems in code and figure out how to make something work.. but he also has very little ability to emote via email which makes people angry.
I wish Debian with their move to eglibc. It will be interesting to see how much code will need to be fixed due to various glibc assumptions people may have made over the years.