Oops House is the simplest looking box in the series, and is described on the KCG website as having a lock. However, it is very easy to accidentally open it before you even feel like the lock is a problem (or notice it in the first place).
I think I liked the looks of Design Housing the most, it has a lot of nice little details an contrast in the wood. However, this one opens with a very simple single move which you'll likely find as soon as you pick it up.
The concept behind this Four Color Palace puzzle is that you can change the color in the windows. The solution is fairly simple and not unique, but it did take me a minute or so to find it. As I mentioned, this is probably my favorite of the group.
Sharp Roof House looks nice as well, with the pointy padauk roof. The windows and door are nice details too. I'd say this is slightly harder than most of the other puzzles in the series (other than Four Color Palace), but this one-step solution probably won't keep you busy for more than a few moments.
So in summary, I'd say they look nice, but they're not nearly as good as the small box series, cake series, or cube series. To be fair, I thought they would be pretty simple based on their descriptions, but they were even simpler than I had expected, with four of them being quite trivial.
I think Four Color Palace is the best of the lot, and Sharp Roof House comes in second. If you like the look of them and want something quite simple in your collection, give these a shot, but don't be surprised if they're simpler than you expect!