Assembly was pretty easy, and it is much BIGGER than we thought it would be! I thought it was a little flimsy.... but we decided to let the kids see what they thought. To let our boys know that this was for our 16-month old, my husband titled it "Cutie-Castle". Here is a picture of it from Christmas morning... before the kids came down.
It was a huge hit with both of the boys! It does stand on it's own, but it is very easy for the kids to knock it caddywhompus. Little K tends to forget that he has to duck in order to walk in and out of the door, but he is getting much better about that. We have even started coloring it. He hasn't done a whole lot of coloring yet, so I am doing most of the work. He does sit there with me and play with his crayons. :) He has left his mark in a few spots, which makes him very proud!
Overall, I think this is a great gift for kids. You do need quite a good bit of room for one of these, but my kids have had a ton of with it so far. I think if they had more options, we would end up with quite a few of these in our house. My favorite features are the doors and windows.