I've taken down 6 colossi so far, and I have mixed feelings about the game. The environment is expansive and beautiful, but it's also pretty much empty. I appreciate the absence of tedious enemy fights, but I wish there were a little more to interact with. The battles are somewhat varied, and the combination of puzzle/action makes for some fun gameplay moments, but once you solve how to grab onto the colossus, it's pretty much just a matter of holding R1 and stabbing a couple times. The storyline is also pretty sparse, but I suspect that may be intentional.
It might get more amazing later on, but for now I'm just finding it to be average.