I could never get into that game, i don't understand what you are supposed to do. I loved ico though. But they both looked good on PS3 (i have the HD release)
At its simplest it's a game of puzzle-based boss fights and lonely exploration. It's a little odd at first because a lot of the normal gameplay/filler just isn't present. You find your Colossus, you have your boss fight and figure out how to defeat it. The exploration is present in the purest sense of the word; there's no mini games, no optional dungeons, no side quests. You explore to find the next Colossus, or just for the simple joy of seeing the world the devs have created.
Emotionally though, you're literally in an empty and forbidden land which means Agro becomes highly significant as your only companion. The fact that the devs made Agro control like a real horse adds to the emotional attachment. Then there's the expressions and actions of some of the Colossi that make you doubt your actions. Wander has a singular purpose in the game (hence the fact the game only really has boss fights), but the fact that these little nuances in some of the fights make you question his/your actions I think is quite significant.