ZombiU and its remaster on the newer consoles and PC are truly a missed opportunity for something great. I should also mention that I finished it.
So, I consider it a missed opportunity because damn it, the potential is there. Dead London, heavy atmosphere, lots of darkness, monsters jumping out from every possible corner. If you've seen 28 Days Later, then you understand exactly the atmosphere that the title is trying to convey. There are moments that will scare you a lot, while also reminding you of Condemned!
The whole scenario with the survivors is also very original. In ZombiU/Zombi, you don't control a specific protagonist. When your character dies, someone else automatically takes their place, and in order to retrieve your lost supplies, you have to return to the spot where they died and loot their corpse (if they didn't die from falling or explosion).
If they have turned into a zombie, then you will encounter a zombie when you arrive and you will need to kill it. Quite a unique implementation, I would say!

Unfortunately, here is where the good words about the title end, as Zombi suffers in other areas. A lot!

- The gameplay mechanics are archaic. The combat especially... it's like something out of the PS1 era.

- Quite a few bugs here and there, which further dampen the already mediocre gameplay.

- The graphics are unacceptable, and the use of blurriness and green filters strain the eyes way too much. Basically, in several parts, it's like smearing butter on the screen.

- The frame rate ranges from 30 to 18-20. Yes, really! A tragically low number considering that this game barely reaches PS3 levels.

- One would expect significant improvements in the transition from WiiU to next-gen platforms. But where are the improvements? They are ignored...

+ Terrifying/claustrophobic atmosphere throughout (streets, houses, parks, palaces, subway stations).

+ Very good sound, intensifies the suspense.

+ Difficult. Think of it as a Demon's Souls with zombies.