question from novice

I?m sure the people on this forum has a lot more experience about this than I. An uncle recently passed away and left a Patek Philippe. I?m trying to figure out if the watch he left me is real or not. He was the kind of guy who owned real high end watches but never wore then, anything he wore were all fakes because he didn?t want to damage them. I?ve haven?t ever seen him wear this watch but then again I?ve never been into watches really. There weren?t any tags or an original box. I?ve gone to websites but have not found a picture that matches what I?ve got. It seems to be automatic, when I shake it second hand moves, although it doesn?t sweep smoothly like a Rolex for instance. I?ve been told that this is a bad sign, but other people have told me it doesn?t matter. Any help on this would be greatly appreciated.