Watch one of those "making of" movies for Half-life2. It tells you exactly what went wrong. Gabe Newell watched what the team had assembled for him. It was a 20 minute dialogue interaction (a story), and he said, no, get rid of that, it's too long.
Then later, Gabe broke them up into groups and had them work on segments. That's why the game feels all broken up. The airboat/dune buggy ride is all done by one group. The Ravenholm is all one group. City17. One group. These groups are further divided into subgroups. The groups did not speak together well enough. This is plainly seen when you are in ravenholm and have well-placed map breaks. Then you get into the city and it seems that you're loading every 13 steps. Nobody was helping eachother! And Gabe wasn't even overseeing the project. When they thought they were done, he was shown the game. He stayed out of it so he could be objective. He stayed out of it to the detriment of game cohesiveness.
This game isn't terrible. It's a good game. It's a fun game. It's a good-looking game. It's interesting. Multiplayer is welldone. It's a good time. It is just that for single-player, FarCry is better. The environment is better, the freedom is better, the AI is definately better, and the story is told to you. WTF does Ravenholm have to do with the story at all, comrade? Anything? Anything at all? It's just a part of the game that feels thrown in. We never find out why the Starship trooper bugs are in the sand, who put them there, or why. The game is like a bunch of little games slapped together. It is not game of the year in the mind of a thinking gamer.