[ubuntu] upgrade to 16.04

It depends on whether you're willing to take the risk with your system. I had to go the upgrade to 15.10 directly route (not recommended, and I was somewhat nervous about it since I dual boot Windows 10), and then received the notice for upgrade to 16.04 immediately. If you know how to get around using Linux commands fairly well, then I would say go forward. If not, clean install or as suggested by Impavidus, wait 3 months.