https://lunoxscans.com/series/got-dropped-into-a-ghost-story-still-gotta-work/ this is where I read it mostly but it's not the best translation
Someone told somebody else that there's more accurate translation in here: https://www.reddit.com/r/DroppedInAGhostStory/wiki/index/
For me it took me a month or two since I'm not that fast of a reader and I was busy at that time
But it is truly worth it, i read other things and seeing a lot of shows but it's the one that stuck with me the most, it's so good at keeping you on your toes and making you think and question a lot of things, and it does give most the answers (still waiting for part 3 ). it's better to not spoil anything on yourself since it has some plot twists...
for info abt the novel just check the other comment! as for my opinion, since im on vacation and i get really immersed in reading a lot so it only took me almost a week to finish :'DD (consider it as 10 reading hrs per day lol).
as for your question, "is it worth it?" hell yea. it's so peak to the point i got attached to the characters </3. after reading the novel there's like a feeling of loss (ifykwm) a feeling of wanting more. the feeling of you can't read another novel again for sometime because the novel u last read hit you so hard. soooo read it! i promise you, it's good. (๑•ㅂ•)و✧
it's definitely worth reading, trust me !! take your time with it because everyone's reading pace is different, for me, with other KW novels, it usually took around 3–4 days to reach 100-150 chapters, some people might take longer since each chapter can be pretty lengthy (around 10+ pages), but honestly, GSGW isn't a novel I'd recommend speed-reading, it's the kind of story where you'll want (and need) to pay attention to (almost) everything, the dialogue, the descriptions, the little details, the seemingly insignificant scenes, every sentence feels like it serves a purpose, and that's what makes the reading experience so rewarding !! :D

after some days! I've finally finished the novel before the chapter 1 drops, and all i can say is it's peak! (ngl i feel like there's a void when i finished the novel, i want more) waiting for part 3!