Don't care much of the linearity, for example I love doom3 and it is a linear game, at least linear as hl2.

Don't really care about the look of the levels in hl2, they're cool if you like the decaying modern city mood (which, in this case, I don't: too clean and polite to be immersive).

It's the gameplay the problem, too emphatic, I didn't like the combat and, as others pointed out, some parts were too long, the driving parts were really stressing. 

a few months ago, I found myself pretty immersed in it and wondered about my own earlier criticisms if they be of sound mind (okay, okay, try not to spurt whatever you are drinking), but then came the spider demon thingies, and for some reason which I haven't properly digested as of yet, they ruined the whole damn thing for me. I was having a lot of fun up to that point. 

I didn't get very far. In the first map, every time I got up to the point where you encounter the first acid lion, HL2 crashes on me. There is no way I can progress further. This is only about maybe, 5 or 10 minutes into the level.

Shame to. It looked like a nice map pack. 

hl2 is amazing. The only complaints I may have are lack of challenging soldiers (combine soldiers are too few and die too fast) and maybe the excessive slowness of the player (left 4 dead is much more fast paced and I like it better).

Apart from that, the series is simply amazing, with a lot of spectacular and amazing things to see and do. 

Thanks for all the good feedback.

Orl: You have missed a button right after the Vortigaunt opened the gate for you. It's on the right, on the Combine terminal. Press these buttons to keep the door held open so that the Vort can follow with you. I'm considering making some custom voice acting to help players avoid this problem. 

I've been replaying Doom 3 and it's been boring/annoying the hell out of me. I'm playing games less these days though - I still love quake, but I play it like a fucking robot. It passes through me like sleep.
Half life 1 and 2 both really stimulate me though. I don't get tired of replaying them very easily. I just wish people were still making maps for HL1.