My iPhone 4's main home button started to fail several months ago. Having to push the button many times to return to the home screen, then I started having to press harder and harder. A few weeks ago it just became impossible to use. Still in contract could not just jump into a new phone, so started looking around for solutions. Enter ifixit.com.
I ordered the $15 part, took just a couple days to get here. Cracked open a Diet Pepsi and dug in. The website walk-through is brilliant, the photos help tremendously. It took roughly an hour or so, with me painstakingly keeping track of what screws went where, then dropped a screw in the carpet and had to sweep the carpet with a magnet to find it, so that slowed me down a bit. But otherwise, the repair went perfectly to plan, and for $15, its like a new phone. Even my "never take apart your watch son" Father who was in town was impressed the we'd taken the phone down to its chassis and got it back working in one fell swoop.
one item of note. At Step 5 in the guide, when removing the battery, there is a small metal piece that came out when I removed this screw and removed the battery. I can only assume this is what they were referring to when it says to "remove the contact clip from the phone". Another photo to show what this is might be good there. Other than that, it was a perfect tutorial, and my phone is back to new!