I rather like buiding stuff in creative in Minetest, and this mod is the perfect companion. With a large block pallette screen to the right, it makes it much easier to browse for blocks than with the default interface.
My only issue with it is that I can't shift-click things into the bin by default, but that's a really minor complaint.
It has all the important features and handles compatibility really well, but it's hella ugly to look at. I always use my own reskin.
Other than the appearance I'd say performance is the only big issue, but overall it's the best inventory mod.