Should I update my iPhone 6 to iOS10?

Here is how I deal with OS updates. I do not update until something that works now, stops working or I can't use a new app I like using, because it stops working with the current version of the OS I'm currently running.

Or I wait until the update has been out for awhile and been tweaked due to problems it had when it was first released. Android, Apple, Windows and even Blackberry have had those sort of OS issues where something stopped working or things started glitching that were never an issue with previous updates.

I also can't think of any time another person with the same phone I happened to have had at the moment, has remarked on which version of the OS one of my phones had or why have I not upgraded.

If your phone works fine then leave it as is.

IOS10 will put more demand on your phone than it was originally designed to do, so it will slow it down. Many of the revised apps you'll have to update are also far more bloated and resource hungry.

Cosmetic appearance apart, for your phone there is no real benefit using IOS10. The definite risk of a sluggish phone isn't worth the non-existent benefits in return. If it was a 6s then you'd be fine, but not the 6.

I've not noticed any difference at all on mine..

It's a phone, It works..

Though I do only ever get the maximum storage ones; if you have a 16GB ?? one, you may need to free up some storage and/or do a backup, update and full reset, then restore, to ensure you don't run out of storage or the update be corrupted during the install.

A factory reset clears everything except the working operating system and preinstalled apps, so nothing is left over to take space. Restoring from your backup then puts back just the things you wanted installed, so giving maximum free space.

It's always a good idea to do regular backups through itunes anyway, in case anything goes wrong during an update or the phone gets damaged or stolen etc..