What I have seen of this game so far was a lot of empty landscapes that you traverse with a horse to kill a few bosses.
That's exactly why.
Shadow of the Colossus is a game unlike any other, and I don't mean that as a hype hyperbole sort of thing, I mean it just as it is. There's really no other game like it. It's a game that isn't as concerned with ticking the boxes gamers expect from any game as much as it is with just being a captivating experience with an awesome story. It feels like a game that was entirely built around this narrative in fact, which is the opposite of what any Nintendo game would be.
Which isn't to say you should expect it to have a very engaging narrative either. The story is subtle, as is mostly everything in this game, and it takes you a while to truly begin to grasp what's really going on. In fact when I first played this (I was 12) I was confused as hell at the end, because I didn't think this game was anything beyond "kill giant monsters!!" and having great music and graphics and such - it was only looking things up later that I began to understand what it was all about.
That said, I don't think anyone could possibly enjoy this game too much if they go in expecting it to be the masterpiece everyone says it is (and it is indeed). It creates a scenario where it's just never going to live up to the hype, exactly because it doesn't have most of the things you'd expect from any game.