Unique art style that successfully creates a very lonely atmosphere.
Reasonably challenging puzzles.
My only complaint is that about half of the challenge is "finding" objects or "places" to click on that look no different than random litter scribbled on the floor or elsewhere. Because objects, or directions to travel in, are not always apparent nor sufficiently differentiated from the background it made hunting for those last few birds an unpleasant and tedious chore. The cursor changing to a hand and stating locations on the lower right helped and was what I deem a necessary inclusion, however lack of the latter in the "hard to find" areas detracted from the fun factor.
Lastly, I had to resort to a walkthrough to become aware that the birds were even necessary. I did see the scribble on the wall of a bird and an egg, and I did see the pedestal with the dots that lit/darkened, but there didn't seem to be anything in the game itself to hint that the pedestal was somehow related to the birds.