Ubuntu 5.04's Nautilus crack (close windows when you open a new one) is intensely irritating. I hope they fix this before shipping CDs. Otherwise, it'll really spoil people's first impressions of GNOME, and it'll be difficult to be so enthusiastic when giving them to people.
I'm not sure how the decision was made, but I'm pretty sure that someone should have listened to Jeff, who I guess would never have wanted such a dangerous change at that point in the release cycle. And just when Ubuntu was being a poster-child for release sanity.