I just finished this game for the first time... like... yesterday or the day before.
I thought it was a very beautiful and atmospheric game. My only complaints are how fucking annoying killing those damn lizards can be, the way the camera moves (I had to stop playing constantly because I felt like I was going to vomit, and sometimes the controls would interfere with the angle and vice versa; this was particularly frustrating when on the horse fighting a colossus), and a problem I had with the two smallest colossi- they have a charge attack that knocks you senseless, but the moment you recover from it they can use that same attack again.
One thing I didn't get was... why was Agro so huge? The horse seemed unnecessarily large, to the point where Wander looks like he is going to pull something when he uses the bow with the way he's splayed across her back. For that matter, Wander moves like a complete dork. I laughed pretty hard the first time I noticed the way his arms move when he runs.
I also would have liked it if they had included a first person perspective option; you could always charge your bow to look around but then the bow cursor is floating around when you're trying to enjoy the scenery.
Two things that particularly impressed me were the lighting effects and the music (and the lack there-of in places). The lighting gave the game an other-worldliness while the music intensified the atmosphere. It was suspenseful, exciting, and very masterfully integrated.
'A great deal of thought and effort must have been put into the game' was my thinking while playing it.