Backups, like spare tires, are something you hope you never have to use. But when time comes that you need them, they'd better work. The thing about backing up any site run by today's modern CMS systems is that you have to be sure to back up the files (programs, photographs, documents) at the same time you back up the database (users, content, categories) to make sure one doesn't reference something the other doesn't have. We back up all our client sites on our server nightly to a machine that's sitting under my desk. Yes, I'm old-fashioned in that I don't trust a backup I can't physically touch. We keep the past five nights' worth of backup as well. So if something goes awry it should surely manifest itself within five days and we can recover from it. The other thing about backups is that once in a while you have to actually run the fire-drill and make sure the backups can be restored. I did that this morning with the openfacesystems.com site itself. Yes, it worked just fine. Breathe easy.
Of course, after Joomla 3.5.0 shipped, a bugfix was released. This was for minor annonyances, such as if you were logged into the administrator side of the site and you got logged off due to being idle too long, you had to log in twice to get back in. This sort of thing. We've updated all our client sites as of April 7th.