I have been building the balsa kits for over 15 years now. I have a bunch of guillows models. The overall construction is not that hard. However with guillows and several other companies you may find yourself cutting out the die-cut parts more than you should. They are also pretty flimsy material compared to others. They do make nice looking models when they are finished. The instructions are easy to read and follow. A company that I have found that has sturdy construction and makes nice models to put together is Herr Engineering Corp. The first one I did from this company was a p-51, it was like I was dreaming when I was putting it together because all of the die-cut parts were nicely cut out and they used excellent wood for them. All the spars were nice and smooth and evenly seperated. Overall guillows is a fine company but if you want more quality and durability then I would go with Herr's. By the way I have flown almost all of my planes through free flight. I didn't want to fly the Red Barron Tri-plane or the P-51 because they came out so nice.