While more technically impressive than its predecessor, and having multiple fun characters (Glados talks a lot more here, most of her popular characterization comes from this game, whereas in the first game she was really kind of uninteresting) the good story and characters are marred by a series of terrible puzzles in the underground sections and a love of making people do long walks and hunt for tiny, distant patches of portalable surfaces. Partly this is done to allow time for the extensive dialogue, but at times it feels like long walks for the sake of bloated environmental storytelling about the rise and fall of Aperture. Ultimately this means that it's not actually an improvement on its predecessor, just a very different game that's reaches the same overall quality through very different means.