I know this has been mentioned before, but I think it's worth posting again. It would be really useful and a better UX if searches included tag hierarchy. Or at the very least gave users an option to enable a hierarchical search of tags. For example given three tags where apple and banana are children of fruit:
I add two notes, and tag one apple and the other one banana. Currently if I search 'tag:fruit' nothing is returned, but that is not intuitive given that I've organised my tags hierarchically. What I believe is more natural, is if I search 'tag:fruit' thej it should return anything tagged fruit, apple, or banana.