I recently tried it on Deck and it's rough, but I think a lot of people only have a deck as an option to play it, so they use what they have. It's a fun game, so it makes sense. If you have the option to play on a PC, it's not worth using your steam deck though.

I play it on the deck all the time and it's fine, graphics turned down to potato but they still look decent, and the FPS stays good in all but the most insane of situations (I play on difficulty 8/9, so I'm experiencing the most enemies possible). Only "hard" part is there's no aim assist for controller so the high precision weapons like snipers are harder to use, but that doesn't stop me from trying haha