Sad, but I've got an OIII filter that I've only ever used twice, on NGC 2070 and NGC 2359 (Thor's Helmet). Generally there's a pretty poor contrast gain/light loss ratio on a small scope like mine but the OIII did work well on these.
With line filters like OIII, match your usage to the particular objects. Tarantula and Thor's Helmet emit very strongly in OIII and hence respond really well to an OIII filter, as Kev said. There are lots of other objects too - Veil Nebula, Dumbbell Nebula etc.
Good luck with it Gem, look forward to more reports!
Cheers -