Last month, 16.10 was released. I guess this would be considered a "point release." Is there anything about point releases to watch out for, or is it generally safe to upgrade for them?
It almost seems like I'm asking a dumb question, where the answer would be the generic "back up your wallet and keys files first, etc.," but maybe there is more to it.
I'm also curious about whether there were issues with Monero when Ubuntu went from 14.xx to 16.xx, if it is relevant to the title.
I see no correlation or problem with upgrading your OS as related to Monero and I can think of no reason why the upgrade would create any problems for your Monero. As you have your mnemonic backed up, you are safe either way.
However, I hope you have taken time to set your "privacy" settings on Ubuntu. Contrary to other Linux distros, there is a little bit of anti privacy behavior. Nowhere near the massive privacy invasions of Microsoft and Apple, but there is some in Ubuntu also.
As is stated in another answer upgrading your OS version shouldn't have any major impacts on your Monero security. However so long as your OS is in maintenance and is receiving security patches (Which is the case for 16.04 as it is a LTS release) there also is no issue with skipping the upgrade either.
