My wife's iPhone 5 battery was definitely on it's last legs.
It really only took me about 20 minutes to complete the repair, but I spent time in advance watching several videos on replacement. I then turned on and paused the iFixIt video to use as a reference, set up a station of sorts, with separate receptacles for the different sets of screws and any associated plates (i used the packing box trays), and got to work. The tip about the adhesive strength for the battery was good. I did watch a less helpful, generic YouTube video about the process and the one good thing I learned is that the releasing adhesive makes tiny cracking noises, and recommended a gentle prying force until that minute cracking noise occurs, then go to a different pry spot and repeat in sequence, always with just enough force to get to that point of a slight release and then moving on. This resulted in the battery popping out easily with a minimum of force being applied at any single point.
The iPhone 5 replacement video was well done, but the top 720p resolution didn't allow for a good glimpse of the screen cable connector removal process. Those cable are clustered into a small area and it's a bit difficult to understand how they are laid out initially.
Also, the video didn't cover re-assembly. It's pretty much a straightforward reversal of the disassembly, but I've had to install a lot RAM chips and such in my time, and it's easy to put back in a cable without really snapping it in there, and then getting an error. It would be a nice touch to advise users to make sure each cable fitting is securely in place. Nobody wants to have to disassemble and re-check!