Congratulations, you've joined Mario's party.
I just had to make a joining the party reference. Anyhoo, I'm going to rebut the only viable argument against Paper Mario I've ever heard.
Paper Mario is just Mario, he'll just be another Dr. Mario.
That is not a fair comparison. Paper Mario would not be a clone, he could have a unique moveset using powered jumps, his hammer, and even partners. Secondly, he's not really just mario, he's actually an Illustration of mario. This makes him more like a different version of mario, *cough*toon link*cough*.You can say neither of those things of Dr. Mario, who is a clone in a costume.
That being said, let's look at the good things.
Has his own series of 3 games, (2 of which were excellent,{It should go without saying which one was absolutely awful}).
He is a highly wanted character.
He has original and unique moveset potential.
He can represent Mario RPG games as a mario spinoff, allowing Bowser Jr., or even better, Toad, to be the new mario rep.
He's uber.