I believe that despite it's harsh difficulty, it's tightknit and small game space allows for rapidity of play and restarts, the puzzlelike element is there because each restart has the exact same variables and mostly same reactions (Same respawn point, same enemy placements, and the placement of the power you have to get to start fighting back,) it works in your favour for the most part as progressing through these tight levels rapidly is fun and satisfying.
Each level usually lasts a minute or so, and even in that space you can die handfuls of times, it's very nice and rapid that way with it's constrained rooms. The problem is that it makes me feel like each room only has one solution, even if it technically doesn't, I feel that the design needs to be a bit more open in that sense, like having more than just the one power available in the room at start for example.
It's probably just that you needed the time to test out a variety of level types really. Otherwise, it's perfectly fine as is.