Will the episodic content model work in the long run? While no one really knows for sure, I'm remaining fairly skeptical. Gamers are used to paying their $40, $50, or even $60 for a complete game (although the term complete is fairly ambiguous, especially since game lengths differ so drastically). Forking over $20 for a game snippet is something new. Something that, to some people, is fairly frightening. Whether sales are strong enough to warrant doing it again remains to be seen. Valve has apparently announced that there will be three episodes, the last of which should be available around Christmas of 2007. That means that they are at least willing to take the risk. And I salute that boldness.
It's my hope that the quality of this episode will match that of the original game. But can a 4 to 6 hour game hold up against its 40 to 50 hour parent? I don't think we'll really know until after June 1. The strength of the Half-Life world lies in the powerful story telling. With any luck, it will be just as strong as it always has been.