This is a great mod, and a great port of a minecraft mod called Ice and Fire which does exactly the same things to a T. It would be better if that was mentioned in the description, as while this mod doesn't reuse any assets or code it's clear where all of the ideas and mechanics came from.
Disregarding that: good mod, visually pleasing, and deserves recognition for that.
A great experience when you know what you're doing, but the crusade against formspecs makes the game very hard to pick up. I recommend adding an in-game guide of some kind, as I initially thought this was a terrible game before actually learning what it is.
Overall a good game, 8.6/10.
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.