I'm sorry but...I don't see why so many people like this. People have constantly told me about how this is the most immersive, well paced and well written game ever made and how it shines above others and how it uses wise gameplay mechanics such as a wide arsenal of weapons and no regenerating health. The weapons are nothing special, just your generic standard FPS weapons minus the gravity gun, which was ammusing at first but became annoying after awhile. The characters seemed rather flat, the only thing I can honestly say about most people is "they're nice to me because I'm awesome" not exactly anything to write shome about other than that they go through a couple of good emotional moments, Alyx getting angry when her father was betrayed I could get behind, but apart from that these characters didn't really stand out from all of the others that I've seen in the past few years.
Also the puzzle system feels really gimmicky and really forced, for a game that is universally praised for immersion, I have to say that stopping to stack a bunch of boxes on top of one another for figure out how a pully system works, that breaks the immersion for me, it becomes very clear that I am playing a game because stuff like this would never ever happen in the real world. The combat is, for the most part, ok. Fair and stable and the assualt rifle's secondary weapon is fairly ammusing but apart from that it's pretty bland with me just fighting swarms of the same enemies over and over again. This last complaint is rather personal and slightly nitpicky, but the level design just bugs me. Something about Combine building design just bothers me, it feels like it's just a bunch of scrap metal slapped together and it doesn't reflect servents of an interdimensional empire that well, in my opinion at least. Other levels feel repetitive, generic and oddly dirty for no real reason.
Overall, not bad, but not the groundbreaking, immersive best game ever made that I've heard about. The sad thing is that I was really excited when I got this game, thinking that I was in for the ride of my life. Sadly though, it just didn't deliver.