Was having issues with my GPS not tracking me and my phone was out of warranty. I did not want to spend $300 on a new phone or even wait for this years new model, so I decided to replace the antenna flex cable, as that seemed to be a possible cause for the GPS issues.
The instructions were super clear and easy to understand. I went slow and made sure to keep all the screws in order and to not break anything. After I reassembled the phone, I turned it back on and still had the same GPS problem. So I opened it a second time and wiped all the connections down with alcohol in case I touched anything with my fingers. I also made sure each connection was tight. After the second reassemble, GPS location got way better, but it didn't totally fix the problem, so there could be another inherent issue with the phone. But everything else is working perfectly, so at least i didn't ruin my phone by opening it and I was able to get it to a much better working order than before, worth the time.
Take your time, make sure every screw goes back exactly where it came from since they are one of a few different sizes. I am happy I was able to at least get the GPS to work more than the majority of the time with this repair and I learned a ton about how to replace iPhone parts. It really was way easier than I thought it would be, especially with the second teardown and reassembly.