The Half-Life series has changed a lot since the original in 1998. Beginning with Half Life 2, and especially starting in Episode I, the series took an extremely narrative focus gameplay not to unsimilar to a T.V. series such as Lost. Half-Life Episode II has some of the most emotional scenes I have experienced in a video game. Period. There are sections that made me want to reach through the screen and stop something from happening, without avail.
Although it does focus heavily on the storytelling aspect, it definitely does not let up on the trademark Half-Life style action. The action is well-paced with great times of complete and terrifying silence followed by a good thirty minutes of constant battle. One complaint regarding episode I was its short length. Episode II definitely picks up the slack in this regard, although some would still consider it too short. Personally, I found it a good balance because there wasn't a lot of extra junk to just make it longer. It's like watching some crappy director's cut of Chronicles of Riddick.