Just started playing GTA IV on the Steam Deck after having it sitting in my Steam library for years. It's really fun. I really like the protagonist, the setting, and it's openness. It's a bit more tame than GTA V which I have played as well and I prefer the more subdued tone.
My only issue with IV is that Niko's constant agonising over not wanting to kill people anymore is at odds with the general gameplay of GTA; a game where you'll probably end up killing at least one innocent person on your way to the mission, let alone the dozen or so cops/criminals you'll kill during the mission.
The ending really got me though. On my first playthrough I drove around the city for at least an hour real-time trying to decide what to do.
I really dislike Niko as a character due to that hypocrisy, but it's 100% intentional. The guy he's trying to find throughout the game calls him out on it when they finally meet. I'm unsure if deliberately making the protagonist unlikable is artsy or pretentious.
My main issue with IV is that the driving camera is too damn low. My abiding memory of IV's gameplay is having to constantly manually adjust the camera while driving, otherwise I'd crash into obstacles my own car obscured from view. I don't know what the hell they were thinking when they made that or how it got past the first round of playtesting.
You just unlocked that exact same memory, holding the right stick "just so" to make the camera usable. I seem to remember needing to lead turns in the same way too.