I have replaced it myself when it hit 82%. The difference was quite noticeable and definitely worth it. I use my phone lightly (phone calls + messaging), thus it would last around 1 and half a day. Now it easily lasts almost two full days without recharging! 12 mini is still a beast and I personally love it a lot due to its size and performance capabilities :D
Nevertheless, I've ordered the part on my own and would not recommend it if you have never opened phones before
Surprisingly enough I live in EU country and Apple Maps is as precise as it gets. All streets are constantly updated, even major roadworks are added almost instantly.
P.S. I live in a small EU country, not Germany or France