How well do you find it runs day to day? That's what really matters I guess. And what are your views on the screen.
SD810 was just never meant for 20nm.
For normal every day use such as browsing, social apps, camera, etc it's completely fine, no signs of slowdowns or anything. Although I am using a different browser from Chrome which seems to allow it to use the high performance cores. Battery life I'm averaging on 4/5 on-screen time, would be nice if it was a bit more.
For most games performance is completely fine, the Adreno 430 is not trottled or anything and is allowed to run on maximum performance. However, I have noticed in more CPU dependant games, after a while you can notice a hit in FPS (Lara Croft GO on max settings feels like 20 FPS, while the lowest feels more fluid). Either way, the A53 cores actually outperformed the Krait 300 cores in my old M7 which surprised me.
Another thing I noticed is for some reason, apps that can take advantage of 64-bit SoCs detects the UK/EU/Asia version of the OP2 as 32-bit (Such as PPSSPP). Checking with an
ABI checker the phone correctly reports it supporting arm64, and even reports the same thing as the US version (which gets correctly recognised as 64-bit), so these apps aren't taking full advantage of the phone (unless they have a standalone 64-bit APK).
The screen I have to admit especially on lower brightness, the colours do look a little washed out. They added a colour balance and while I do see a difference all it does is either makes the screen more blue or more yellow, and the results seems to heavily vary with each panel looking on the OP2 forum. But on around ~20% brightness (which I've settled on), the colours are fine. It could do with a little more punch, but it's bareable.
Yes, the phone does get hot, but only the top part of the metal rim, which my hand hardly ever touches. And even then it was not as hot as my M7.
I did play around with AK kernel for a bit, and yes, it actually does solve a lot of these problems. All 4 A57 cores are allowed to run at the same, and it significantly improves performance where it matches other SD810 phones, temperature wise it doesn't even feel that different from stock. There's even KCAL support which significantly improves the screen colour accuracy with the right settings. I moved back to stock however as I wanted the easy OTAs, AK kernel was a bit of a pain to reflash every time a new OTA popped up. However, it does show with the right software, this phone can perform a lot better.