I've been using vim for about 2 years now, for my editing needs which are just taking care of my linux systems, writing little programs, and taking notes. I'm not sure if I'm 'used to it', but I can generally get it to do what I want done. I still press 'u' (undo) a lot, and I take frequent trips to the help menu ":help help". There's still features of Vim that I haven't learned to use so well yet (registers, macros, ex commands, vimscript). I think you can grasp the basics in minutes to hours, and depending on how deep you want to go: your time's the limit.

I can second this. That how I started. The biggest problem is to memorize the commands. So a cheat sheet is a nice addition.
I can recommend, in addition to above, to learn one extra command at a time, and then use it whenever it is appropriate. There are many ways to do something in vi, only one way is the most efficient. So when you are used to the new command you automatically use it, introduce the next new command.
I would place the tabbed editing (:tabe filename, gT, gt high on my list of extras.

And if you end your post in LQ with :wq you know you are tired.

jlinkels

vi was the first text editor i used when I came to linux, so I am pretty much used to it.

I myself had some trouble with it at first, but now Im just fine with it if using it as a quick way to edit text, conf, and other files in a terminal. Other than that, I use IDEs and real text editors like LibreOffice Writer.