Not that deep into tech but I started off with a Redmi Note 3 (Kenzo) in its release on 2016 and used it for 4 years, it wasn't used heavily just moderate browsing, clicking images and bla bla.
After a while it started to show signs of being outdated (no software and security updates) with how rapid mobile tech got, brought a Samsung M31 in March, 2020 which was my daily driver till a few weeks back.
Now this phone on the other hand worked flawlessly for what I needed, basic stuff, gaming wasn't as bad just couldn't expect it to use max settings for graphics and security updates still came from time to time (I think now its stopped). Recent life changing things has happened in my life where me as a person wanted to start treasuring memories with a better camera and this phone just didn't have what it takes. Started to look around for a camera to purchase but eventually decided that a phone with a good camera was all I needed instead of the extra hassle of camera and all the accessories you'll need.
After quite a lot of digging and looking at different phones, I was initially looking to go for another mid-range like the M31 but eventually got my hands on an IQOO 12 (16GB Variant), glad to say it has definitely shown to be an amazing upgrade and decision in under a week of purchase itself. Yes, there were other options but as an overall package this phone had a lot going for it.
The few things I'm really impressed with are:
Camera - My primary reason for upgrade was to get a good camera so I'll start with this. Coming from a M31, almost anything above its range should make me go wow but damn this phone has a nice camera, my wife and I recently went to a wildlife park and the zoom really helped me get some great pictures of the flora and fauna which was really far away from us, the portrait mode is the GOAT feature of this phone though and the macro seems to also be miles ahead of most other phones in the range.
Really quick finger/face unlock - Having never experienced this, the unlocks are really quick that I can just slide unlock with no delay in almost all light conditions with the face unlock feature. Both the sensors have yet to fail me in unlocking at one go.
Charging - While my daily life has no requirement for having really quick charging times, it has definitely helped me twice till date where the quick charging made it easier for me to not wait around for a comfortable range of battery percentage to head out for travel. Did I mention you get a 120w charger with the phone, I still think it's a scam that most flagship phones don't provide a charger in the name of environment.
Security - Since it's a new phone and that too a flagship from the brand, 4+ years of updates is something which will keep me using this phone for a longer period unlike the Redmi Note 3 which ended at 2. Ton of banking and other apps on phone without latest security updates is probably not a great idea.
Display - All I know is its crisp and I can see everything clearly at very bright areas. Phone works smooth with the 144hz set at hybrid mode, don't have a requirement for it to run at 144hz at all times.
Only con I would say is I miss a headphone jack, these phone companies really be removing features here and there to make it harder to decide for a better upgrade.
Honestly, I don't care about most of the features the phone has but the number of pictures I've clicked already surpassed the M31 in its span of 4 years and that to me is already a worth it reason for purchase. There were people saying the UI/Software was bad, but I don't seem to see any or maybe they are just looking for features that I have no need for. Gaming is better as I checked COD Mobile and it worked great, having had a reference point with the M31, would say it runs way more smoother and HQ. Don't play much so the SoC doesn't get used to its full capacity but as a daily driver it's been a great experience.