Thing is, while visually this is nothing short of absolutely stunning, there are SERIOUS issues with gameplay. E1L3 is one particular offender in terms of enemy encounters, particularly two spots matter here: the initial two skirmishes on narrow ledges where you're attacked from every direction by barely visible and quite quick enemies - but then there's puzzles, too and confusing level layouts. The teleport puzzle in E1L3 is one rough customer (after the Iris combat) but the Minos secret level is not only a bitch to find but also a bitch to complete, a quintessential maze where it's barely hinted at what you must do to get past this.
E1L5, the mine secret level takes just about one of the worst levels by Cliff Bleszinski (Foundry) and somehow manages to make it an even worse maze than ever before. The level directly preceding it is also quite confusing at times. Same goes for E1L6: Seti (the light-the-torches puzzle) and Moros (one or two locked doors that can't seem to unlock no matter how hard the player presses what is strongly hinted to be the only button in the room and thus the opener for 'em). I ghosted through some sections after finally giving up on that. E1L7... only now I am starting it but I am fearful of what I'll encounter. This isn't enjoyable, not to me at least. This is torture. The levels particularly in part 2 take the worst tropes of what mappers like Bleszinski are known for (which is mazelike, confusing construction) and elevate that to a whole new level. I'm not one for cutting entire rooms so streamlining them is not something I'd suggest but maybe a bit heavier usage of NPScripts to add short cutscenes helping the player would do just fine. I mean, come on. This is not a proper challenge, it's an exercise in frustration.
Aside from the visuals one more thing deserves praise: the beta weapons and beta monsters. As well as other monster variants, yes, even the barely visible frustrating ones. This is much more variety than ever in stock Unreal. You just can't get bored with those.