My power button was broken, it didn't click. I lived with it for over a year (using the on-screen assistive help to put my phone to sleep) and it sucked. The repair is listed as a hard one though, and I didn't want to risk breaking my phone. Finally my phone was old enough that I decided I could risk it.
The repair went great, and the phone works perfectly now. It took longer than I expected, and there were several spots where I got frustrated trying to get tiny parts on or off, but in the end it all worked out.
Be patient and careful. Use a piece of paper off to the side to keep track of all the screws and parts. Have a big block of time set aside where you won't be interrupted.