One of the things I was most notably surprised about was the upgrade in graphics - good. But it seemed to be lacking for fire and explosion effects? I played a lot of firebug and demo in KF2, just felt like zero improvement if not even a step backward in FX there, which was disappointing, given the gfx improvements most other areas.
And yes, played with all settings maxed.
Had some issues with hitboxes, and odd movements from zeds, guns which didn't have a smooth firing animation, overall made the gameplay experience feeling disengaging, something I never had when playing the first 2 games.
Maybe expectations have just risen since then, maybe it's a beta issue and something which will be ironed out, but the experience waned my excitement for release, definitely.
Meta progression, crafting, talent trees, customisation, class abilities all great new mechanics to the game. But at the core, the gameplay experience should be king, that's why people play. Felt like alot more time has been spent trying to make the lobby /jet area fleshed out when it's practically obsolete, as opposed to gameplay/combat experience.