i'm on the fence here. i know its not entirely painfree, but i don't believe there is lasting pain. people argue that cats lose their main form of defense and will resort to biting, etc. i grew up with a cat that we declawed as a kitten. she was an indoor/outdoor cat in a rural wooded area. she lived to be 16, was top cat in the neighborhood (and i had seen the cats she beat up, she was definitely queen), took care of herself with dogs (man could she smack hard), all without front claws. she even caught mice, rabbits, moles, and birds. and was never a biter. so i don't follow that line of thinking. i have a cat now, and since he was 5 years old when i got him out of the pound, there was no way i was putting a cat that age through unneccessary surgery.
now, declawing back claws is just wrong, as these are used for traction. thats just awful to do. we've had some cats in rescue like that, poor things had trouble jumping and playing on the cat towers.
i know they say declawing is like removing our fingers to the middle joint, but of the declawed cats i know, i've not seen it to be a problem. they play, are active, happy, and quite often defend themselves just fine. due to the surgery process though, i wouldn't do it to an older cat.
there are some great alternative though. one is a less invasive surgical technique, where they do something to the tendons so the claws are still there, they just can't retract them. there's also just keeping the nails trimmed or the plastic covers (which dont' work ifyou have a crafty cat like mine who figures out how to bite them off.........).
but really, if you get a cat, get him things TO scratch on and wear his claws with. my cat will occasionally get the carpet, but he's not big on scratching furniture luckily. so i use a water bottle to spray him and keep his nails trimmed. the rescue group i volunteer for (see my signature), won't adopt cats out to people who plan on declawing cats. and i know in california, beverly hills at least, they have passed some local law against it. other states are looking into it as well as pressure increases from animal rights groups.