I suppose you could finish it in six hours, but those are a fun six hours. And you could trot out that "It's not long, therefore it sucks" argument for lots of good games, like the original Metal Gear Solid for instance.
As for not getting the experience elsewhere...if you want Killzone or MGS you can play them on other consoles, and you can always play Resistance 1. You could play the first Uncharted, but the sequel is likely to be leaps and bounds better from all accounts. For that matter, I haven't see anything like the first Uncharted anywhere else either.
Yes, there are plenty of "action" games, but that's a pretty broad brush you're using GP. Oh, the RPG genre is so overdone, Dragon Age is just a waste of my time. No, no, I don't care about any of the details, because it's in the RPG genre and that = overdone to me, I'm going to dismiss it out of hand. My "done to death" comment was referring to its setting (high fantasy), not its game genre.