Quest
I don't think there's too much to be said about the quest to be honest. It was fairly simple, which saves having to give a ton of people directions. It would've been nice if the quest forced people to use the new map search feature. It was sufficient for a holiday quest imo.
I don't know why the event had to delay the new boss though, it didn't feel like much work had been put into it.
Skulls
Is it just me or did skulls seem much rarer this year? Every monster seems to only drop a single skull compared to the earlier events where multiple could be dropped from higher level monsters. You were already condemned to afk in a multi-combat zone last time and I feel this has just gotten worse this year. There's no fun in collecting skulls and if it's money you're after you're honestly better off doing an actual moneymaking method.
Muncher was honestly a nice touch thematically. I like the idea of the skulls only dropping if I have him with me. However I did find myself accidentally picking muncher up quite often and missing drops as a result. It gets especially annoying in places like the abyss with a high monster density. Having him automatically pick up the skulls would've also made this whole thing a lot more bearable.
I'd like to see skulls be obtainable from pretty much anything (skilling, just being online, maybe even forum activity) next year. Maybe have them stored inside your account instead of having them be an item. To see how many you have you'd have to talk to muncher. Could re-name them to souls, that'd make a bit more sense.
I feel holiday events could be done way better in general.