I find it really helpful to cut and paste some of my code, or test out my ideas, using gedit. The software is quick to install and is flexible for use with a lot of different software languages. This is a pure editor that is, in my opinion, the premier notes app for coders.
I would recommend Vim in any scenario where text files have to be viewed, created, or edited on GNU/Linux computers. Regardless if you need to quickly change a few things in a configuration file, or you need to write up a full document, Vim is great. I wouldn't use Vim to view, edit, or create anything that requires "rich-text". In other words, if you need to format the text (bolding, font colours, word-art, etc), then Vim isn't the tool to use.
I don't consider the steep learning curve to be a hinderance on the overall usability. I would rate this a ten, but to be honest a lot of people do get hung up at the beginning and just abandon it. However, for people who have made the moderate effort to get over the hump, nothing can be more usable.
There is no commercial support for Vim. Thus, it will not get a mark beyond 5. However, community support is very good. You can easily find solutions for most of the problems in the community.
gedit is very lightweight and intuitive to use- its simplicity is its biggest strength. What you are using here is a pure editor, so it's very much like a more helpful, intelligent version of your basic note-taking application. I find other comparable applications may offer more options, but they are also less intuitive and therefore less efficient for my note-taking needs.
Vim's keybindings are a lot more complex than Notepad++. With that, comes a whole bunch of capability that Notepad++ just can't match. Emacs is comparable, in terms of capabilities--because Vim is built into so many unix systems, I chose to learn it instead of Emacs. Knowing both probably isn't a bad idea, but there's enough to learn in either camp to keep you busy
