iOS 11 was decent to good for me on the SE. Performance was good and relatively snappy, though there was stutter here and there opening apps, and the overall snappiness was worse than 10. As for battery life, you'll be losing about 1/2 hour to an hour of usage (based on standby time, which eats up battery on 11). I downgraded to 10.3.3 because of how exceptionally smooth it is, but I think I'll be back on iOS 11 once .1 or .2 comes out.
honestly, am having an excellent time on my SE (btw, i have ALWAYS had 'reduce motion' on). so, happy with the speed, stability, and performance (even despite the few things i don't like on the new os). key word in this post: happy.
Very strange, for me ios10.3.3 was laggy every day and I had less battery on it, compared with ios11. Both formated and configured as a new iphone. Battery still very far away from 10.3.2
does the messages app in iOS 11 on the SE now feature contract photos in the message list when you open the app (like 7 and 7+)? Or is it the same plain list of names we've had since iOS 1.0?
Just updated my SE, feels fast and responsive, no complaints here at all.