Mike has an LG G10 phone and it keeps bugging him about updating. He's been waiting, though, to make sure that Marshmallow is OK. Leo says it's fine, and he should go ahead and update. The battery life improvements alone make it worth it.
Mike is also waiting to upgrade to Windows 10. Leo says he'll have until July 29th to get the free upgrade, but if he has Windows 7, it's a harder choice. He could do the update to get it free forever, and then downgrade within 30 days. But he's qualified to go back to Windows 10 anytime after that. So he should upgrade now, and then can choose to downgrade within the next 30 days if he doesn't want to keep it.