Pros: Spiderman and Hulk characters are cute and fun for our 4 year old boy.
Cons: Extra pieces do not stay together. Blocks work but walls collapse very easily!
The bottom line: Buy a different kit!
I gave this to my son as part of his Easter present and it has been the vain of my days since. He tried so hard to put it together. His father tries so hard to help him. And yet it falls apart in the midst of it each and every time. Is it the blocks or the builders? I tried it. It won't stay up. If there was a "satisfaction guarantee" I do believe I would be using it.

You get 31 pieces in all.
14 - Mega Blocks
2 - Tree Tops (1.75" x 3.5")
2 - Tree Bases (2.25" x 1.25")
1 - Slide (7.5" x 2.5")
1 - Ladder (5" x 2.5")
1 - Flag
2 - Fence Pieces
2 - Wall pieces (4.5" x 5" and 4.5" x 4.5")
1 - Pole
1 - Radar
1 - Radar Base
1 - Base Plate (5" x 5")
2 - Characters (Spiderman and The Hulk) (3.5" x 2.5")

The problem? The walls won't stay up. Maybe if there was another base plate for support? But you are supposed to use the base plate as the top of the little play house that you build. You take the two walls and put them on each side and then put the green plate on top. The problem is that the walls just buckle and fall off as you try to hook the slide and/or ladder on to the top. It just all collapses. Then comes the frustration as my strong willed child who does not give up easily tries and tries again to recreate the picture on the front of the box.

The blocks are typical so they lock together normally. It is the extra, unique pieces (walls, slide, ladder, fences) that just fall apart at the slightest touch.

I bought it on sale at a discount store for $7.50. So at least I didn't pay retail price. But I think this may disappear soon. The idea is great but it isn't worth the frustration by either our child or us! Had not had this kind of result from Mega Bloks before. Although I don't think we have bought this medium size before. We just have the bigger size in this brand. We have Lego brand in the smaller size and he handles those just fine.