A lot (I think). I actually got the idea from datastorage, just I wanted to do it in a more straightforward, simple, and documented way. I think that datalib give the mod developer a lot more control over where and how their data is stored. You could honestly store or access data anywhere using the resources that datalib offers, whereas datastorage seems more limiting. From my understanding, datastorage puts all the data in a type of table, which creates a lot of limitations. However, though datalib automatically creates a directory in the world folder, developers are free to create their own directories or files with datalib.mkdir and datalib.create. To me, this gives a lot more flexibility. It doesn't only allow storing things in the world directory, but you could easily access resources inside the mod directory as well. Overall, I find it to be much more flexible in what you can do. Yes, datastorage still has it's uses, but I find that the flexibility I have in datalib makes it much easier to work with.
Mods Using datalib:Here are two mods that use datalib, both are written by me, but the point is to see how it can be used, not to show that people actually use it (no one does other than me, as far as I know).
ServerTools (WIP, but functional) - genesis.lua, filter.lua
digicompute (WIP, not functional) - api.lua
PS: I've won every round of Hungry Games I've been in for the past month, except for when I voluntarily quit because I started to feel bad for everyone else.