Still a great game even after all this years.

The only things I've found annoying especially considering the last achievement (speedrun one) were poorly responsive controls. This doesn't happen all the time as some sections can feel really really smooth, but I feel like having character react to almost everything around them (like putting hands on the walls or tripping when mashing arrow keys) should be allowed to be disabled as they are just pain in the a when trying to beat the game quickly.
Also, the checkpoints on this game could have been more frequent and more thought off.

For the positive things we have pretty much everything else. Interesting level design and world building,
fun puzzles,
ambient,
camera work (most of the times),
and of course the detailed climbing animations, which might not be a big of a deal for most people, but I've found them to be an example of devs just not being lazy and paying attention to our immersion.

I won't spoil anything, but if you don't get goosebumps during the ending you might not have a neurosystem.

To summarize: Should you play this game? Yes.
Should you 100% it? Hell no...