There are two reasons this game scores the same (and not higher) than Half-Life 2.
1: It was more buggy (The person I was escorting disappeared once and I had to go back to a previous save, and once during gameplay a triggered event never triggered, and again I had to reload).
2: A large part of the action in the middle seemed tedious and uninspired.
On the whole, however, this addition to the Half-Life story was well thought out, well executed, and it left me dying to start Episode Two once it ended. The way they tell the story is so immersive and meaningful, I truly feel like I can forget about life and immerse myself in the game--a feat that few other games are capable of.
I don't really have much more to say except that this is a continuation of one of the best games ever, and if this is any indication of what is possible through episodic gaming, then bring it on.
Game Title: Half-Life 2: Episode One
Platform: Xbox 360
Genre: First Person Shooter
Release Date: 10th Oct 2007