I forgot I played Metro several years ago in my PS3. However, I gave it a try to beat it again.
I never got bored about this game, given in my second play through. You need to be aware about the age of it. It is not a 2017 or 2018 game, so do not expect any exceptional.
The story and the atmosphere are to things that the game gets you in. It is not the best game out there but it is a classic, must play if your are a gamer and track all the games out there.
It is a hard game even in normal difficulty. But it is one of the things I like about it.
Also, it is not a long game that makes you feel you are wasting time. Just a very straight forward game from beginning to end.