To say that Heavy Rain is a fantastic gaming experience implies that the game itself is being weighed against its contemporaries, which is pretty much impossible. No game I've ever played has so profoundly moved me and caused me to think of the medium in a new light. There's art here, but I wouldn't call it an "artistic" game. There are horrific situations, but I would never call it a survival-horror game. There is a very cinematic quality to the game, but even here, I wouldn't call it an "interactive movie."
Put simply, Heavy Rain is a gaming experience that took huge risks in design, narrative, and game mechanics, and executed on its ideas to masterful effect. You will care, in the end, about the decisions you made to shape the fates of your characters, and wonder long after it's over if you made the right choices. Most of all, I hope that it will send a shockwave through the media industry as a whole and prove that video games can in many ways be the best medium to convey a story, and are more than capable of stirring up infinitely complex emotions; namely, love.
PROS: Superbly crafted story; believable characters; expertly evokes an emotional response from the player.
CONS: Some may not be willing to accept the breaking of traditional gaming concepts.