5 - 30 minutes
Power seemed to be running down faster than before.
Took me about 10 minutes. The Pentalope driver included with the kit fit perfectly and the replacement went without a hitch, although it does take a bit of careful prying to get the old battery out. The included pry tool worked like a charm and should come in handy for other projects.
My advice is to attach the battery plug before pressing the battery into place. The small, ribbon connector requires a slight bend and this will happen automatically if the plug is attached first and the battery pressed in second. Also, have a clean work area with lots of light and a place to put the tiny screws. Otherwise, no tools needed except what comes in the kit.