All you would expect but in the end too short.

User Rating: 8.7 | Half-Life 2: Episode One PC
Suffice to say that Half Life 2: Episode One is everything you would expect it to be. If you enjoy Half Life 2, you will enjoy this. The action is fast paced and the game never really sits still, you’re always in the action. One minute you are rescuing hostages the other you are fighting Combine troops, you can’t get more action packed than that. It’s very fulfilling.
You also spend a lot of time with Alyx, and the game evolves around getting out of city 17 with her help. Although the developers attempted to create a sense of need for you’re AI partner this is not the case. For the most part she can shoot other zombies and open doors but aside from that she just follows you around. There are some fun parts where she really seems helpful but otherwise it’s kind of missed. However, although Valve neglected that point they really struck hard with character development and it really allows the story to progress naturally and brings forth many questions.
Other than that I finished the game in a measly 3-4 hours although it was supposed to be about 8-10 according to Valve. This is the biggest let down from the episodic release but nonetheless the developers include commentaries which might excite the most hardcore fans and adds a couple more hours.
Overall the game is still a hit, its fun, progresses the story very well and the price is just about right. I say go for it.