The level designs, lighting, puzzles and plot are a masterpiece in their own right, but in doing so the game clearly pushes the boundaries of the technology required a little to far.
This title not only gives you an AI companion that walks alongside you on your journey, but actually relies upon it to complete most of the puzzles. Any video game with an AI companion suffers from the issue of the Artificial intelligence falling far behind the flexible and rational intelligence that is expected, however, whilst it can be slightly frustrating the companion in this game is years ahead of other titles, it looks and acts in a rational manner and its animations are flexible enough to adapt to nearly all scenarios. Any issues can be overlooked but if the companion were another humanoid rather than an animal it would be more obvious. In this respect, when the boy your are playing as becomes unresponsive or performs an unintended action, it is far more frustrating. Similarly, although the camera follows your avatar without player control you are left to suffer some horrible and confusing angles at times.
If your are a fan of Fumito Ueda or linear-puzzle games then this is a must play game, if however, you are looking for fast paced action games then this is not the game for you.