Just save your big guns for the demons that give you an issue. You can spurt a little bit of ammo on the small demons so you can punch them for more hp and ammo.
Platforming. What can I say. It's the most basic thing I've seen. It can hardly compare to that of a platforming game. You magnetically snap to stuff you can grab onto/boost off of.
Conserving your ammo has always been a big part of doom. You get punished hard for running all out, despite there being a handful of ways to replenish. If you're all out, it's simply your fault. That's how the series has always worked.
Simply put, just don't buy games because there was big hype surrounding it. Purchase games that are of your own genuine interest. Stop letting others speak for your wallet.