15 minutes - 1 hour
After several years of use we noticed the button on our iPod Photo was getting difficult to press. Then, the wheel wasn't working quite right - self-scrolling through the menus, going back to the root menu, etc. I determined that the battery was swelling, putting pressure on the controls.
I found a replacement battery and repair kit after a quick search on iFixit's web site. Following the directions provided, the repair went very well. The photos helped tremendously in making sure I was prying, pulling, and sliding at the correct spots. The only difficulty was getting the swollen battery out of the normally form-fitting slot. After a little careful prying it finally popped out and I was able to quickly wrap up the repair. Total repair time - about 25-30 minutes.
No enlightening ideas - iFixit had it all covered. Having a small pair of needle nose pliers handy helped in removing the battery cable.