Yeah, that's the reaction I had when I started playing it recently. It has not aged well.

Looks fine.

But it's still boring. /comeatmebro

That reminds me: There's this one place in the driving section (level "Highway 17") where you are supposed to open a gate by finding and installing three big batteries to the engine which powers the gate.

I LOLed at that point, because I remembered that when I first played the game, I had not noticed the whole battery thing, and instead I was able to proceed by making a ramp out of the broken cars and crap with the gravity gun, and I used that ramp to jump over the gate with my buggy. Or it could have been that I was pushing the buggy with my gravity gun along that self-made ramp, and pushed it over the gate. And then walked to the other side myself too and continued driving.

I think it is great how the physics engine let you solve a problem in a way that the developers probably didn't intend, but it still felt fully believable, and didn't break the game.

It kinda is. For entire game I felt like I have to travel 15 minutes from point A to B and at the point B I get some nice levels, and then it's boring travel again.

The story doesn't help at all.

My favourite part of the game is still a level with a crane where you can kill people with metal containers... :P

The texture resolution (of environments, walls, floors, etc.) was kind of 'meh' even when HL2 was originally released, but the facial animation, water reflections and character models still look pretty good even now.

The facial animation in HL2 looks better than that used in many recent games

While I don't really believe that Half-Life 2 is a pinnacle of gaming graphics (I have met such people), it aged very well IMO. I played it for first time a year ago and the visual quality surprised me.
On the other hand, Half Life 1 looks like a trash. However I used to say that even when first 3D games had been released. Wow. Sweet mod.

The Source Engine has never impressed me for its graphics, more often than not, the games look a little below average to me.

the only exceptions for me are Portal and Vampire The Masquerade: Bloodlines and that's because I liked the games' art style

It does look rather nice, but that new Alyx model makes me want to barf. There's nothing wrong with her old style and its design is way better, so I don't get why they felt it to be necessary to turn her into a generic pretty girl.

I was checking out landscapes and skipped characters' innovation. *checking* Uhm, I guess the comment "Good thing the Combine waited for her to put makeup on and let her have collagen injections for those lips." fits perfectly.