vi (or vim, which is what vi symlinks to in modern *nix distros) is my preferred command line text editor. Those who are new to Linux are often confused by how vi functions. It can definitely be a challenge to figure out how this text editor works if all the text editing you’re used to happens to be in Notepad.
Actually, vi is quite easy to be tamed into “usable” mode, ie. to edit a few lines of text here and there. However, in order to get the most out of your vi experience, you might want to check out the graphical vi/vim cheat sheet. It will definitely improve your productivity while editing in vi.