I can't see I mad this "transition" as the keyboard is still my main instrument, but I did pickup the accoustic after playing the keys for a few years (self taught).
While I'm not a skilled guitarist in any way shape or form, I can play adequate folk-rock accompaniments. Even some fingerstyle.
I'd say you probobly have an advantage on people strting from zero, because keyboardists usually take the time and effort to learn theory and harmony, which would be usefull when playing guitar.
It's a totally different animal. You'd find that it's easier to get passable results on a guitar than it was when you first took up the keyboard, but it's a lot harder to master.
Oren