my iphone 4 (original issue) battery was not lasting for a day and the home button was working erraticly, so i did a web search and found ifixit.... what a great website for information and the supplies
the repair went as i expected, the online video and written instructions supplied by ifixit helped tremendously, i did have to take it apart after i got it together the first time because i did not seat the home button connection securely but after the second attempt all worked well, my battery is fully functional again and so is my home button. it took me about an hour and a half to complete the repair.
be patient, take your time and you will be fine. kudos to the ifixit team, you are the best, i am sorry i didn't take any photos...