Easy fix, and now the battery life on my 4S is great!
After more than 4 years of use, my trusty 4S had to be recharged multiple times a day.
It all went reasonably smoothly. I used an extra pair of plastic tweezers to avoid touching any small bits with my fingers. The guide was great and some of the comments had great tips and alerted me to the trickier parts so I was able to do those slowly and carefully to avoid any trouble.
Just do it! This was so much easier than I thought. I wish I had done it a long time ago.