Ok, I applied the update. Obviously it hasn't been running on my phone for long, so these are first impressions and it might be in my head. :-)
One thing is, the whole system seems to be responding much faster and smoother. Not that it was slow before, but transitions seem better.
On a bad side, my pictures have a purple tinge around the outsides. The center looks great. I thought it was possibly from being in the Otterbox Defender. Took it out of the case, and had the same effect. On the other hand, the rest of the pictures actually seem clearer than before the update. Again, it could be a placebo effect. I'll have to do more testing. Right now, all of the pictures I have tried since the update have been inside with not great light.
The NFC notification icon is a bit distracting. It feels huge up there. I guess it is nice to be able to see for sure that it is on, but I haven't really done anything with NFC anyway other than just playing with it back when I first got the phone.
The quick settings from the notification pull down is quite handy, and a very welcome addition. I suppose I can get rid of my toggle widgets now. :-)
Overall, seems to be a good update so far. :-)
OK, I have had a bit more time to mess around with the update. Apparently the purple hue around the edges was related to poor lighting. Using the camera in a brightly lit area, the pictures look fantastic. Don't know if it has anything to do with the update, although I don't remember having that kind of issue on my phone prior to the update.
One other annoyance I have found, is that it is now notifying me in my notification bar, that the charger I am using is slow, and recommends I use an HTC charger. While this is good information to HAVE, it isn't causing damage, and there is no way to get RID of the notification. This is an extra charger I have at my office and have been using all the way back with my old Evo3D, and for months with my One. I know it is slower, and am OK with that. Unless there is some reason this could damage things, I would prefer to be able to make the notification just go away. I wouldn't even mind if it popped up every time I plugged it in to that charger, as long as I could swipe it away.
Also, I didn't notice it added a new VPN app. That is somewhat helpful, although I don't NEED it on my phone right now.
Beyond that, everything seems to be working pretty well still.