Not sure if I'd say the Lycoming O-235 in C152 was dreadful...
But back to the OP.
I have a bit of experience with the RR O-240. There were quite a few of them in FRA150 Aerobats here in Ireland. The issue with them is there are no replacement crankshafts. Once you're out of metal on the shaft your out of luck and your plane is retired or re-engined. A prop strike, and your SOL. I had a O-240 core and the guy who bought it had tried 80+ leads to try get bottom end parts for his. There is a chap in Netherthorpe who is the specialist in them, but he wont sell you the crankshafts he has in stock as he needs them for his fleet of FRA150's.