Re: HL3? What's the point?
"In fairness, you've got to compare it to other shooters at the time, and on that basis I think it holds up well." -Steve Crook
This is exactly what people need to keep in mind. Half-Life 2 came out nearly NINE years ago at this point, and had spent around five years in development prior to that, so of course parts of it are going to look dated by today's standards. When it came out though, it was a lot more open and interactive than most other shooters. Sure, the level layouts were rather linear, but Valve provided lots of interesting things to play with within those environments to give players unique ways to approach situations.
One of Half-Life 2's biggest selling points was the relatively large number of physics objects within the world, and your ability to interact with them using the gravity gun, explosives, and so on. Previously, furniture and other clutter within games was mostly static, while in Half-life 2 it made for a dynamic source of cover, obstacles and improvised weapons. The game also brought interesting drivable vehicle segments into its gameplay, which was relatively rare among shooters at the time. And then there were friendly NPCs tied into the actual gameplay, which was something else that was pretty much unheard of in shooters. Sure, they lacked any sort of advanced AI or anything, but they were much better than anything else seen in comparable games at the time.
Another thing the game did well was that it made the most of its linearity to provide a highly "cinematic" experience, more so than any other games I can think of from the time, expanding on what the original Half-Life had done before it. Since then, many other games have done the same, and it's become something of the norm, but this was rather innovative at the time.
"But after playing the Fallout series, I definitely don't want to bother with Halflife again!" -Brian Miller
Aside from the obvious fact that Fallout 3 came out four years after Half-Life 2, they're arguably not even in the same genre. As has been said, Fallout 3 is more an RPG (or rather CRPG, if you want to get technical), where the focus is much more on placing people in a sandbox environment and letting them do what they want, than on providing a cohesive story with careful pacing. Sandbox-style games can be great, but that doesn't mean there's no room for games that tell stories in a more controlled fashion. Both provide different kinds of experiences.
I suspect Half-Life 3 will contain more open environments, but will continue to be much more linear than something like Fallout. Fans of the Half-Life series aren't looking for such an open, non-story-centric experience where you could spend dozens of hours crafting thimbles and taking quests from locals, instead of saving the world or whatever it is Gordon Freeman is doing. That kind of gameplay simply doesn't fit what most people want from a Half-Life experience. I do think Half-Life 3 will again try to be best in its class at various aspects of gameplay though, but it's difficult to tell what those might be at this point.