Had a play through the first level and it is good old doom, albeit to me it seems harder than dlc 1, which in itself was harder than the main game.
They introduced more annoying enemies that are countered only by a single weapon type or single game mechanic. But they have also introduced the hammer as a mechanic to get more ammo/armour on an aoe scale, which should in theory help spice up "low ammo" game mechanic.
On the one hand it's a great game but on the other hand the low ammo thing annoys me a lot, especially on difficult levels when I just end up dying many many times because I just ran out of ammo on all weapons on on that specific weapon that counters that specific monster in a tiny room and now I'm about to get killed whilst I'm looking for a low level demon to slice up with a chainsaw for ammo.