The update installs a green MS Store icon on your taskbar without your permission, big hint there. Also, when you edit a shortcut on your desktop and open the Properties window, there is a new box on the Compatibility tab: "Enable this program to run with OneDrive files".

on the Metro screen, but I don't see it on my taskbar.

On mine, it asks about SkyDrive files, but that looks like a feature-- I use Dropbox and Evernote and haven't needed SkyDrive so far, but if i did use SkyDrive, I'd like the option to work on stuff in the cloud without it being the default.

This was the first time I've ever seen it on my taskbar.

Not that I use it much, but the update broke IE 11 for me. Won't start. I did a system restore and then updated again, excluding the two IE Explorer updates, but same deal. Internet Explorer won't start. Maxthon Cloud Browser works, as do all of the other browsers.

The update also changed at least one file association (jpg) for me both times.

I'm going to restore again and ignore the updates for a cycle. I'm pretty sure my system is locked down well enough to be able to afford missing an update cycle.

noticed any file association changes.

Every version of Windows different people have different things happen. Go figure.

I'm going to stick with the update and try to figure out how to fix the problem. It'll give me something to do. Funny thing is, if I make IE 11 my default and open it from the Metro screen, it'll open up in a Metro window (but not when I click on a shortcut or link), but with no functionality. Just a blank Metro window. Nothing happens if it's not my default.

I've tried:

Removing IE and then adding it via Windows features.
Resetting everything IE via Internet options.
sfc /scannow

it's tough to believe it's gone or completely nonworking.

A setting buried somewhere?

It was a conflict with a minor security startup, Emsisoft Background Guard. Everything was co-existing before the latest update.