Every minute of this game is entertaining!
The sound effects and lighting are superb, providing the most thrilling half life experience to date in my opinion. The story carries on from episode 1 following Gordon and Alyx's escape from city 17, with a new destination in hand. I'm not going to present any of the story, as you really need to play this game, as it is definately one of the best games out there. The gameplay is the best of any FPS i have played, and anyone interested in shooters or games with a fantastic story should pick up this game and play it.
If you haven't played half life 2, play it and then episode 1, then this as trust me this will not dissapoint.
It is a short game, but thats because its a third of a game, however is better than most games out there, even some of the 100+ hour RPGs. The game is also relatively cheap compared to other games, and if bought in the orange box is certainly worth its money. There is no excuse you must own this game.