This tower is a great starting project if you're looking to get into 3-d cardstock terrain. It's price is good and it is not horribly hard to put together while still getting you the practice with some of the less simple processes to see if it's something you want to do more of.
It's useful in many situations. They've listed it as a guard post, but it can work for any small tower. Personally I'm using it for the ruins of a long abandoned wizard tower and it will suit those needs nicely.
The only problems I had putting it together is getting the first level to fit into the sleeve created on the second level. It just doesn't fit. But it sits on top in a stable way that still looks decent. Also the small roof on top of the tower didn't come out as a great fit for me.
But the rest of it worked better than I would have expected from my previous experience doing these things. Braces for holding on the roof work perfectly. Other areas where there is some risk of showing mistakes or white spaces are well filled.
I have fun working on it. It makes a great addition to my collection. All in all, good set.