I dropped my phone in the ocean in August and it had numerous problems afterwards, like the power button sticking. After a while though, everything sort of went away except that the lighting port didn't work as well, my headphones cracked, and my battery just wouldn't charge properly. I decided to replace the two parts instead of buying a new phone. I like the size of the 5s and I haven't found that Apple has updated past its capabilities yet.
First, I found it was really hard to hit the sweet spot between pulling on the screen to lift it and not yanking it so hard that I pulled it too far. I snapped the home button ribbon and just about dispaired until I noticed that it had come apart at the connection. Otherwise I carefully followed the instructions on iFixit and found them very good. I popped the connection for the volume controls out by accident and found it a little hard to put back, but it was really no harder than any of the others. I got one of the battery stickers to pull out as it was intended but broke the other so I had to use a card to scrap it out. Putting in the lightning port was a little tricky, especially since the iFixit guide doesn't outline how to transfer the parts you need to keep from the old hardware to the new. I got everything back in the case and closed it up and the phone works great now! This repair took about two hours.
If I thought I was going to have to get into this phone all the time I would totally pay for the case opening doo-dad that it sold on this site, but I found a regular suction cup work well enough. If I did it again I might have someone hold the case so that it doesn't get yanked open. It was really helpful to heat the back of the phone to get the stickers out, so I would recommend not skipping this step. I used a magic bag, which I found worked really well. I would advise reheating the phone after pulling out the first sticker, as that is probably what led to the other sticker breaking in my case. In order to see what parts to switch to the lightning port hardware, I would consult the comments, but it would be really great if the iFixit guide was a little more helpful. Two of the little pieces weren't too hard to figure out, but getting the port for the home button in the right spot was a little tricky.