I loooooooove (one O was not enough to express)
Evernote, however, one significant deficiency is that it only supports one level of directory categorization (Notebook->note) instead of multiple, like a directory structure. I contacted them about this but they said they didn't plan on implementing that feature.
As a result, the classification of my notes is too simple and insufficiently indexed in an only one-level hierarchy.
The question here is: is there another web/mobile app which is just like Evernote but supports a multiple level hierarchy of notes?