Well, his barrel allows him to critical hit in an area as well as get more gold for your buck so to speak with his Q so Critplank got a lot better. Not to mention his W now has % health scaling as well with the missing health AND his ultimate can be upgraded to deal more damage without missing out on gold or building AP. Finally, his passive now has ACTUAL scaling and deals actual damage. So, yes, his AD build got a LOT better at the cost of a tiny bit of base health I think. His Q also costs less mana at ranks 2+, so that will help his lane mana problems.
Overall, this rework is a huge buff to the pirate when he builds AD and I am seriously looking forward to it.
As far as how he plays, about the same actually except you get barrels now to lay down pre-fight or in the fight. He plays similar to live, but better and with more teamfight contribution. I personally cant wait to see some comedic barrel videos.