Sturdy. I have resident cats and rescue cats, ranging from 5 months to 10 years old, 6 lbs-18 lbs. All of them like the cat tree, but the kittens dominate the top perch. The little tube-ish thing really serves no purpose for the range of personalities I have,(it seems too small), but it can be removed. My 12 year old son was able to put this together primarily by himself, in about an hour. Competitive price, fast, free shipping, and a great product.