So, 4 years have passed. I remember playing this and get depressed for awhile. Is the DLC worth it? Last time I played there were no DLCs
Short answer: Yes, especially if you enjoyed A-G endings.
Long answer: The 3 DLCs add following content;
1)Chaos Dungeon. A Dungeon Crawler where you can get all the items you missed from failed quests besides keyitems. It also includes unique boss encounters exclusive to it. Not only does it add additional lore viva the skulllanterns but you can encounter old boss characters from BS1 as well. ALSO "Mabel~"
2)Deep Sea. New underwater section to explore. Creepy as fuck in the deeper levels. Enjoy aquamarine horror.
3)Winterbell/Ending H. Adds a new ending + area. On the same unique level like the back-end endings G & F.
Additional NPCs, new quests, items & minor spoiler
short visual novel section.
I would even say ending H/Winterbell is the most kino/peak Toro has created so far.