The side bar was my favorite thing! I often wished Myspace and other sites had one similar. Other wise you have to sift through pile of crap about people buzzing or adding someone. I just want to see my friends posts in terms of photos/journals/videos. Yo.
I also used "Favorites" in my sidebar to keep track of what was being posted in communities. I can't even FIND links to communities, other than trying to find a piece of media someone might have tagged into one.
The sidebar (I've been using the classic sidebar) also puts managing my media right there wherever I am, I can post/edit/manage all of my media types, check my friends, group and topic updates. There are now many intermediate steps to trying to get to those things.
The new Buzznet is way too confusing for me to navigate around, the sidebar was the way I checked out my friend's stuff... now that it's gone I'm completely lost. D:
I also miss the old layout of the front page. :C