MMORPG Aion: Do you have to p2p for the month, or pay for hourly game time?

I was watching vids of this gorgeous upcoming RPG on YouTube and came across someones comment stating that Aion will charge $15 for 200 hours of game time.... I thought it would be roughly about $15/month. Is there any truth to this hourly charge buisiness. If so, it would kind of make me feel like im paying for minutes similar to the way cell pnone companys charge you for minute limits. I love gaming as much as I love to talk on the phone with friends, so I chose a cellphone Co like Metro PCS with UNLIMITED minutes. I would hope to get the same options with my gaming.