A host of "live service" nonsense weighs it down, but it is otherwise one of the toppest games of all time. The action on offer in Darktide is like nothing else. The melee and gunplayed are premium quality in controls, visuals and audio. The enemy variety is impeccable, there is almost always so many different enemy units on screen and are so distinct to one another (guys wearing rags absorb less or more damage from certain damage sources than guys wearing different kinds of armor). The pool of chaff, special and elite enemy units is large and varied, making the game a constant, never ending knowledge check and prioritization judgement calls. It is a high octane blast.

For fans of VT2:
The matchmaking and out-of-mission experience is inferior to VT2.
Some Vermintide 2 fans refuse to move on due to this.

While VT2 is still great, the gameplay in Darktide is utterly next level. The enemy design is completely superior in any and all categories. Chaff is much more varied, the elites are way more fun to fight than Stormvermin / Chaos Knights and the Specials are running laps around VT2's specials in terms of fun factor. Waiting to get a sight at Storm Mage or Gutter Runner is boring, Darktide has no specials that refuse to show up, they are always around and affecting combat until you spot them.

The guns are a no brainer improvement but even the melee combat is better.
Vermintide melee: Either spam lights or heavies to clear chaff. Spam the other one to combat elites. Few weapons are more difficult than that.
Darktide melee: You actually have to learn your moveset and cycle to the desired swings based on whether you're fighting chaff or elites on most weapons. Some elite killing direct swings only come out on the 2nd or 3rd swing in a chain. You might need to remember to do heavy, light, heavy if you want to perform pure direct hits instead of any sweeps, etc. You have to pay attention to your moveset on most weapons.

Music is better too.