It wouldn't be a problem if these updates didn't cause new problems and Apple was more candid in why they were pushing these out. They are usually extremely vague or won't disclose anything as in this latest case. In general, when a company pushes out these types of upgrades, it's either because they identified a known issue and are fixing it, are adding functionality, or in some cases, removing functionality. Very often, these updates do in fact fix some issues but can cause a whole new set of problems. I had fantastic battery life on my personal 6s+, until I upgraded to 9.3.3. Now it is awful.
For that reason, unless you have a major problem that you feel the update will address, don't do it. Wait at least a week, then google "Problems with iOS 9.3.5" or whatever you are updating. If you see dozens of people with the same complaints, the update may have caused a new set of problems.
Since Apple isn't talking about this, I'm going to reveal why this upgrade was pushed out unexpectedly. Recently, a prominent Emirati rights activist was targeted by a simple text message that asked him to click on a link for information on detainees tortured in the United Arab Emirates.Targeted by cyber attacks in the past, Ahmed Mansoor became suspicious and forwarded this text message to Citizen Lab in Canada. They, and the security firm Lookout, both determined that this spyware was very rare, very powerful, and capable of employing his iPhone's camera and microphone to snoop on activities in the vicinity of the device, recording his WhatsApp and Viber calls, logging messages sent in mobile chat apps, and tracking his movements.
It is believed that this spyware was developed by the Israeli firm NSO Group, based in Herzliya. This group is now actually now owned by US private equity firm Francisco Partners Management. You know they are flying under the radar when the company doesn't even have their own website.
Unless you are an enemy of the state of Israel, I would wait for iOS10 and not take any chances.