I've been using Samsung notes for a while now, and it has many useful features, however there could be some improvements.
Tags are good, but at the moment I don't really find them that useful - I might as well just search all documents.
I think it would really benefit from embedding links/portals within a note to reference other notes - like wikipedia. I wish I was able to select a word or sentence (text or handwritten) to convert into a link/portal, which takes me to another note - or even better, a popup of that note - where I can find out more information about this topic. I think wikipedia is a great model for this, and on a notes app this feature would be even more useful, and it would save me a lot of time.