I really like the concept of the possessions giving your ghost abilities or being used to for specific purposes. They all have their place in the puzzles and I think they'd allow for a lot more expansion of the levels based on their different combinations. A very cute game and fun to figure out the puzzles! I think I couldn't figure out the umbrella one, though.
Heads up: I think I soft locked myself in the top left room; with the umbrella. I unpossessed it as it was trying to take me back up top and it froze the ghost in place when they became visible again.