Birth Control Implant or suggestions?

So recently all I've been using for a birth control contraception is the condom method but I know that even that isn't 100% effective. I've been wanting to get on an actual birth control but I don't trust the pill or myself because I am constantly forgetting to take things and my scheduling is terrible. I've been looking into the birth control implant in the arm and I was wondering if any of you ladies have it. Is it effective for you? costly? pain? side effects? and if used, are you safe to have unprotected intercourse. (pregnancy wise) Other suggestions are appreciated. I'm looking for something that is a definite guarantee to not get me pregnant besides absence.

Thanks!