If you're asking how the game is so far, I haven't played it yet. Why is it not on Steam? From what I've read "2K Games did not bother to give Valve new keys to sell, hence why the game is not available."
Just purchased Doom 4 during Steams's summer sale for $35. I'm still trapped in Poland with no internet outside of my phone, so I won't be playing it for a week and a half, but it will be waiting for me in Germany.