The core gameplay conceit of the early levels—dying to turn into a ghost, and solving puzzles by swapping between ghost and corporeal forms—is pretty neat. I like those levels. Having the time you "save" be added together to determine your time limit for the last level is a great idea! It turns the level timer into more than just a high score.
But there wasn't really an indication of what "time saved" meant. I kept getting 0's in the early levels, so I assumed it just meant "how much time you shaved off your personal best" or something...until I started getting positive Time Saved scores. (Obviously I figured it out once I reached the final level.)
Speaking of the final level...it feels like it came from a different game? I guess that's almost inevitable when most of the game is a puzzle-platformer and it ends in a boss fight, but I had barely even used the spell shooty thing after the tutorial where it was introduced—dying and possessing(?) soldiers just felt more natural. I'm not sure I have a solution, but it felt odd.
Also, I decided to walk left through that door thing in the boss fight, and wound up spending all my saved time falling through nothingness. It's my own fault, really, but it's still an odd bug I decided to report.