The main problem is malfunction of desktop apps in the new libertine container. Any option is opened in a new window. Impossible to work with gimp or libreoffice, essentials for me.
See this post on how to fix that
Firefox crashes as soon as it starts.
I don't know what version of Firefox in present in 15.04, but if you want to install an older version of firefox that does not crash in 16.04, follow along with this blog post.