Intro and Ending were charming.
I like the graphics. There are a few grassy corners that look off. I realize many of the tiles don't line up from one to the next, but In a few corners it's more noticeable. (See figure 1.) The waterfalls in the bottom part of the building look odd falling in front of the water. The top part looks fine in this regard, because all the water is covered by falls. In the bottom, however, it's odd. I think you could put the falls behind the water in the bottom part only without losing cohesiveness with the top parts.
I thought the save point placement and number were good. It wouldn't hurt if they were more visible as Polana pointed out, but I didn't find it a problem.
My only dislike is the seeking bullets are hard to see against the sky. Darkening the sky a little will make it much easier to avoid them.
I didn't run into any voids, wall-swims, or other technical problems.
