I had hopes with the intriguing premise, but tons of bugs (or simply poor design) completely destroys the imersion. Once that's done, you realize there really isn't that much here to begin with.
The key problem is the game's interface. Controls are slow, imprecise, and laggy as all hell. Given how often the game is designed to require good timing, fast reactions, and careful item placement, this is a huge strike against it. I'm not sure if this is just poor design or horrible quality control - when I first started the game up I wasn't even able to move due to being spawned inside the floor, and even though they've fixed this the entire screen is constantly shaking (except, occasionally, when I jump and it snaps into stability) and there's a persistent damage indicator on the screen flickering on and off with varying levels of intensity.
Unfortunately even if this were patched, it would not be enough to make Twin Sector a good or even passable game. Frankly if you were to fix the controls, get the screen to stop shaking like my character is having a constant seizure, and speed up the response, you'd be left with a series of puzzles that are disturbingly easy. All of the difficulty in the design comes from the fact that you're fighting against the controls, and this frankly is not acceptable these days.
As for the visuals and atmosphere, I was left sadly unimpressed. Environments are blocky and I'm pretty sure frequently using textures ripped straight from Half Life 2, with nonsensical machinery designs that seem to mock the very idea of immersion. It's obvious that Portal's influence is showing here in the level design, but sadly the devs didn't seem to realize that a key reason that the whimsical insanity in Portal worked was because it was in an environment intended to be a puzzle, and nothing else. Once you left the testing chambers, the world was almost disquietingly normal.
Unfortunately there is no such conceit in Twin Sector. This is the real world - a real world where apparently engineers felt you should design a life support generator with a computer console you can only get to if you walk up three flights of stairs, turn off 2 superflous lasers on a catwalk that seems to serve no purpose whatsoever, and then jump 20 feet straight into an open topped cage over the generator's core. The best part was that once this was done the floor dropped out of said cage so as to let you back out into the room - making that sole console completely inaccessible. Just a little bit of creative set design here could have fixed this. Sprinkle in a few broken consoles, dress up the lasers a bit more to make them look like they're actually part of the reactor rather than just arbitrary obstacles, and you actually start forming a cohesive, functional world for this story to be told in. The makers of Twin Sector obviously either didn't know how, or simply didn't care to put in the effort.