HL2 was absolutely worth the hype. Depending on your taste in video games and your expectations based on other experiences in the FPS genre it can difficult to see what HL2 did that was so different.
First up, art direction. Valve are Masters of atmosphere, City 17 and it's surrounding environments are so lovingly and almost obsessively detailed. Everything is designed to capture your imagination, from mind blowing vistas to the narrow corridors, every detail creates an atmosphere that evokes an emotion. Note, this is not about technical complexity, it's about artistic prowess.
Character interaction. Not many people give a toss about any NPCs they encounter along their journey in other games. Some are lovable, others not so much and some are just (intentionally) plain confusing. Not an easy task.
Unless you just love to shoot everything to shreds every waking moment Half-Life 2 has fantastic pacing. A huge problem with many shooters is battle fatigue, it's the reason I give up on so many FPS games before I reach the finish. HL2 builds up the fights with brilliant puzzle and exploration sections to divide them.
As for the story, the methods used use to tell it are brilliant. It's not just that everything happens through your eyes, it's that the story is all over the world. If you check out newspapers, propaganda sprayed on walls, posters and what the NPCs tell you, you will have a much greater understanding of the HL universe. All these things can be ignored, but if you wish you can try and peice it all togther, making for some interesting debates.
Amongst other thing. HL2 has the right to be deemed one of the greatest video games ever made, you might not like it if you were expecting one great big shoot 'em up, but it is a fantastic bit of story telling.
HL1 and 2 both have the dubious honour of being the only fps games that give me motion sickness.Must be the engine or something..anyone else get this?
You're not alone. It's something to do with the default FOV I believe. Google it, I'm sure there is a solution.