It's great to see in how many movies the 'Weta-Team' helped! It's absolutely worth it visiting the cave, there are so many interesting things to see and explore!
I'd recommend doing the Standard Tour (1h/$28) If you're interested in how they made the miniature movie "Thunderbirds", do the extended Tour (2h/$45)!
(There are longer, more expensive tours available).
You'll get a detailed picture of how Weta works and how they create all their amazing effects and stuff for the movies!