A great little game that doesn't get much attention. Will definitely be replaying this one sometime down the line.
While Shadow of the Colossus succeeds in creating a very sombre world with a unique approach to combat, puzzle-solving and story-telling, Ico carries many of the same properties, while borrowing influences from Zelda (in terms of puzzle solving as well as the small cutscenes that occur afterwards), setting the game in an isolated, haunted castle and thus creating an experience equally as memorable with a really big heart to match. Expect an atmosphere of isolation and loneliness, an excellent setting with an amazing scale and beautiful environments to look at, and puzzles that don't so much require thinking but more or less exploring every inch of the castle and taking everything in while planning your next move.
Of course, the game isn't without its issues. The combat is really boring and mundane, and many times you may find yourself annoyed by the enemies that the game presents you with. The camera can be a bit finicky at times, though it isn't as bad as several other games. The game is also rather short; and people who are looking for a long, time-consuming experience will leave slightly disappointed.
Aside from those shortcomings; the game still succeeds in making the experience memorable and worthwhile. I'm already considering replaying it again. One thing that I really have to commend the game on was actually making the concept of escorting the "damsel in distress" quite enjoyable. I normally don't take too kindly to escort missions in video games, but I found it incredibly fun and challenging having to navigate the girl and help maneuver her through obstacles. I found it quite enjoyable every step of the way.
This game is worth buying if you like adventure, if you like exploration and if you like games that have a sense of mystery and magic to it. You won't be disappointed.
The game can be pretty pricey nowadays though...especially if you're planning on buying it complete and sealed.