Some good stuff

Peak modpack, it's rich in content, while trying to be as intuitive and fun as possible.
The devs are actively listening to suggestions and the community is willing to help.
The in-game guides are great and a lot is custom made, the pack fits for a lot of playstyles whether it's a slow playthrough, with tech, exploration, combat, or even building.
The rpg part of the pack has been well thought out, the classes system is logic and extremely rewarding from early game to extreme end game for those who want challenges. Some things are currently experiencing the Great Rebalance.
The custom things are as polished as possible, and the pack's development is not finished. More has yet to come in future updates. Also the story is juicy af if we get into details.
I'm afraid to say that almost nobody finished it in a legit world (I didn't too), except maybe some very specific experienced players: even after 500 hours there's still stuff to do.