As for the second shot... GOOMBA!!!
And a proper one, not a Mario-movie one.
Third shot, however, seems pretty rough. The solid black looks like a pit, but you can use the ladder on it? If it's indeed a pit, some "edges" would be good to go with the grass rather than the perfectly straight line it's got now. Probably the easiest thing to do is duplicate that water-edge tile you're using at the bottom of your screen, and fill in the water area with solid black. At least, that's what I've done a few times to eliminate hard edges on pits and shorelines.
At any rate, your dungeons sound interesting. I'm assuming you're going to put these items to good use one you finally get them? It would be cool if each successive dungeon required a bigger and bigger combination of items to get through it, rather than just using each item once or twice. It takes some good design skill to make items consistently useful rather than simply using them as a "checkpoint" before progressing and hardly ever using them again. Though I'd also suggest not going overboard in that regard - nothing's more annoying than having to swap between 4 different items 20 times per screen.
