Super easy! I'm not exactly an experienced fixer, but this replacement took no effort at all. (I also replaced the battery of my iphone 4S: that was much much much harder)
It was harder than I thought it would be... the screws are so super tiny! I had to curse quite a lot to get them back in :)
My advice: DON'T DRINK COFFEE BEFORE replacing your battery! :)
I also had the "searching" problem, and at first my phone wouldn't connect to itunes (error message), but after resetting network settings and restarting my phone, all went back to normal. Curious how long my battery will last!
