I look at it like some sort of legacy game. HL was the true classic but HL2 certainly has it's merits. The problem is that so many games have copied HL's ideas ad nauseum so I can relate to anyone playing it now for the first time and judging it as "nothing special". But in it's time these physics based silly puzzles, driving/boating sections etc etc where all brand spanking fresh. The engine itself was a lot of fun to mess around with (no other reason Gmod was born), so it's the kinda game you have to judge in the spirit of the time of release. I still think they are worth playing if you are a younger anon that goes in with the right expections. The game is still interesting enough to hold it's own in current year. There's also something to be said for the episodes, which really are significantly better than the base game. Really focused, thightly knit experiences on those. And Alyx is a masterclass on how to write female support characters. Holds her own, both in gameplay and story but she's not without faults or weaknesses. Her little breakdowns and damsel in distress moments tend to make most players care for her.

HL doesn't have this "nothing special" problem, it still holds up incredibly well and hasn't really been outdone by any other FPS. Making it the true classic HL without a doubt.