The worst part is grinding and prepping the hull. Proper safety equipment is a must! Other than that it involves basic woodworking to cut the stringers, and a learning curve for fiberglass if you have not done it before. Lots of videos, articles, and advice here on the forums. Take lots of pictures (also post some so we can see what you are working with, so you can get advice pertaining to your situation and not generic advice.)
Also expect to do transom work, usually if one is rotted so is the other.