Looks like you had a good cook. The bark (outside/outer layer) is what most look for. I usually shave it off, chop it up and mix in with the pulled pork. Foiling will give you a softer bark, but you may want to wait more than 4 - 5 hours. Foiling before the bark has time to form, you may loose all seasonings covering the meat. Wait for the butt to hit around 160°F before foiling.