A tiny (wee bit) complain I have with corona is:
When you assign a map to a CoronaMtl slot using the SetProperty command, that slot does NOT get activated by default. Not comparing, but the only render engine (that I know of) which defaults to all maps slots being disabled is scanline, and even scanline gets auto-on once you add a map to a slot using the said command above.
Not a MAJOR complain, not a dealbreaker also. As I see, Corona is getting so mature that I'm picking on the small stuff lately :P
Cheers