[II2II]

I would say that it is worth it for one simple reason: vi and emacs are going to be around for a very long time. This has the advantage of letting you learn and build upon your skills as time progresses. Even though vi and emacs usually take much longer to learn and modern editors frequently offer many more features, you will probably end up being more productive with the old school editors simply because you aren't relearning existing skills every few years.