I find it amusing that an engine that attracts the vitriol above is often described elsewhere as the best light aircraft engine ever produced. Nothing is perfect, and although I lean to the latter point of view when thinking of the O-320 Lycoming, they certainly do have occasional problems. So far my own O-320 is doing well. It's been flown about 1000 hrs total since 1971, never overhauled, makes no metal, uses little oil, all cylinders between 76 and 78/80. I think it's quite a practical engine and was absolutely the right choice for the lightest four seat Cessna and Pipers. Fairly easy to work on too, when required.
I have a four cylinder Continental too, and although it's fine the details of construction make it a bit less practical than the Lycoming.