[Xiaomi 12S Ultra] Mitoraf:
I'll try to give you a complete answer as I can I have this phone since last month, I live in Israel and I use 5G but 5G here is awful in my area (same speed as 4G) even though I have a 5G plan but that is a different conversation,

I have the Verdant Green 12/512 Version I bought it for $1225 from Aliexpress:

1). I don't live in the UK so I cannot say, here the signal is good, even on 4g and 3g (there is no 2g in my carrier so I can't test that), I do have an issue of calls suddenly dropping for no reason (bug in software I assume)

2). The main camera is awesome, the camera experience is super fast and launches very very quickly and snaps shots very fast, also the camera is very detailed, the ultrawide and telephoto are of a lesser sensor and quality is lower obviously, if you don't mind the quality difference between all 3 then it is great camera, front camera is decent too

3), The camera is decent, does the job, yeah it's max 1080p30fs but it's enough for video calls and still selfie (most use of selfie camera), unless you are a phone vlogger you won't mind the resolution and quality

4). Battery life is great for android flagship type phone, why I write android flagship type phone? since there are tiers in phones with different battery life between all of them, iPhone 13 pro max for example is killing with battery life compared to android flagships, only android Midrangers can compete with iPhone 13 pro max, if you come from android flagships you will be satisfied, if you come from recent android Midranger or lower tier, the battery life is worse, to be expected since this chipset is very powerful but also power hungry, I have the mi 11 ultra before this phone, it was decent with battery life and not too good, the reason is the 120hz screen was very power hungry and 888 chipset not efficient,

5). As of writing, I am using latest stable version 13.0.7 and it has issues, camera sometimes laggs a tiny bit when opening, caller id doesn't always work, and even saved contacts show up as numbers, keyboard gets reset to chinese keyboard with every reboot, developer settings get reset with reboot, wireless charging is limited to around ~20w and doesn't work with 50w wireless car charger pro (I have official 80w, 100w desktop chargers and 50w wireless car charger and all don't work well with this phone and they work perfect with mi 11 ultra)

6). Google is available but there are location issues in GPS sometimes, Google Pay doesn't work at all for me personally some had it work, I couldn't, google location history is not working sometimes, issues here and there

7). I am currently okay and a bit happy with the phone due to the above issues, is it perfect? no, is any phone perfect? also no, this is a china import and you need to know what you are doing in order to use it, I plan to unlock bootloader and flash Xiaomi EU rom to fix all these issues above, it should all be fixed with a custom rom that adjusts the OS to locations outside of china and with full google support, I would not swap the phone since it is very good, just needs more fixing of the above.

The Xiaomi Mi 11 Ultra can be bought for less but you have many more issues with it, the phone drains faster and overheats allot, it has proximity sensor issues so taking calls using earpiece and listening to voice messages is a pain, the 888 chipsets is a mess of overheating and battery draining, you will lose battery fast even with basic use, and video calls for long make the phone lag and very hot, I would totally not recommend the mi 11 ultra over the 12s ultra since they fixed all these issues with the 12s ultra,

Basically if you don't like messing around with phones don't get this phone since you will have to do tinkering with it to fix the issues, if you don't mind tinkering like I do it's a great phone and very good competition wise, it has great cameras too, and battery life is wonderful,

I would give it a 9/10, and I only lower its score due to the software issues stated above, after flashing a custom rom and fixing the issues above the rom will be better and it will be a 10/10 in my opinion,

this phone is an ultra phone it focuses on camera, chipset, screen and overall quality and it nails all those points great! I would totally recommend it to phone tinkerers