The level design is by far the best part, the levels are aesthetically consistent, impressive, and unique, and the layouts are intricate and facilitate exploration and effectiveness well. They're big without ever feeling empty, which is an excellent feat.
All of the system design tweaks and changes also worked really well, the new skill system was excellent (though Battle Training was still a bit more useless than I was hoping) and the perks were a pretty neat addition. Making the spy drone an item was a great improvement both in terms of the narrative and the gameplay, though I never made much use of it. The weapons were... well, I still suspect they were ripped out of a version of Counter-Strike, but either way they were nicely detailed, had excellent sounds, and most of all I loved the new implementation of recoil and how powerful it made the weapons feel, especially in combination with dust puffs where your bullets hit. Also loved the tweaks to the weapon mods.
Great economy, too - you actually really needed money in 2027, unlike... well unlike in any other Deus Ex mod I've ever played, as well as Deus Ex itself. Or Human Revolution, for that matter.
The only real let-down was the narrative. Really needed a proper intro to tell me who the hell I was playing as. Never really had enough time to get to know and care about the characters, so I never had any reason to like them or dislike them. The denouement in the end was cool, but it would've been cooler if I'd cared about what happened to any of the characters.
But I get the feeling the narrative wasn't a main focus during development, it seems the emphasis is primarily on the gameplay and especially the gunplay, and I can only applaud those priorities - it's a much more focused game than you expect from a Deus Ex mod, so what it does, it does really well. Completely worth the 11 hours of my life I spent playing it.
Excellent mod, with a quite good storyline, pleasant maps and a sufficient duration. But the best point is the new stuff: the new weapons (including the spiders, drones and new grenades), the new enemies, the new skills and the new augs bring many new fighting/playing possibilities. I actually fighted much differently than in DX.
But there are some bad points. The difficulty goes from very hard in the first half to very easy in the second half of the game. Several times, especially in the first half, infiltration is made impossible for no justifiable reason (enemies who know where you are without seeing you, alarms that sound while being bypassed...), turning from time to time this true DX mod to a basic FPS. Also, I didn't get the same feeling as in DX or in its better mods about the different "factions" of the game: I didn't care that much about the choices I made. And it didn't felt like a DX prequel to me at all.
Still, this mod deserves a 9/10, with a 10 on creativity.