We have had out Sky Fort for about a year and a half.  We couldn't be more pleased with the purchase.  When it arrived on a very large truck, we were a bit intimidated.  However, the precise directions, clearly marked pieces of wood, and pictures in the manual made putting this together very doable for two adults.  

As for the upkeep of the wood, we have not had to maintain the stain color.  The wood still looks as beautiful as it did when we put it together.  The specialty hardware keeps the bolts tight and doesn't seem to need much tightening.