Check "don't collect my data," download, run. Smooth install. Have to shut down Firefox to import bookmarks, etc. Woulda been cool to have it import the tabs I have set to open when starting Firefox.
First thing I think about, notice, look for - extensions. That's one of the things that makes Firefox such a useful tool for me. There are a lot that if they went missing, I'd find myself spending more time doing things. (And I haven't even looked at Ubiquity yet...)