When I was in highschool, I worked at a vet clinic during the summer holidays. At the time I was young and wasn't quite sure what the proceedure was for declawing. It didn't take long before I found out. I can tell you from first hand experience, this is a very cruel proceedure. Just as the others have already posted, it is equivalent to amputing the first digit of your finger or toe.
When the poor cat awoke from surgery, they were obviously in pain and had to be bandaged for a while so that they would not bleed. They couldn't even use regular litter, but had to have shredded newspapers so as to not cause them more pain.
I personally would never declaw my cat and I try my best to educate others who are considering having it done as to just how cruel it really is and to reconsider having it done.