I think it's worth taking lessons.. it'll get you started the right way and should keep you from developing any bad habits that will limit you in the future. I both give lessons and take them with other people, so maybe I'm biased! :D

You can get a fair way with sites like this, and maybe start by learning the open chords, but I've found I learnt far more by taking lessons. I play fusion, and take both electric and classical lessons.

If you can afford it, take lessons...