Almost finished the second level and I need a bit of a break from the constant blood-pumping action. On Nightmare it definitely feels a bit easier than Part 1, the Escalation Encounters (their version of Slayer Gates this time) have some pretty devious enemy combos but nothing quite as bullshit as the hardest part of Blood Swamps/The Holt... at least just yet!
New enemies are more like new variants, but most are pretty cool. The Armored Baron is fun to fight, you can either be reactive in popping his armor or microwave him yourself which feels much better than enemies like the Marauder or Blood Makyr that force you to be reactive. Stone Imps only take meaningful damage from the otherwise useless full auto shotgun mod, but that's alright when you can chainsaw or hammer them for a oneshot anyway. The Cursed Prowler is a nasty motherfucker, getting hit by him disables your dash until you kill him which is a death sentence in many situations. The only variant I really hate is the riot soldier who has an invulnerable shield- you have to use grenades or remote detonation to kill the annoying pests.
Hammer is great, more fun than the Crucible. It creates an AoE that falters nearby foes for an extended duration, refills ammo, and is recharged either by Glory Kills or pickups. But it also has an about second-long animation before you smash it down which can leave you very vulnerable, so careful when to use it!