Sturdy - our 2 Maine Coons like it. Post to top deck is slightly crooked. 
Tips:  to get preferred positioning of openings without over tightening or loose joints, cut a cardboard spacer like a doughnut with a wedge cut out and slip it between the 2 pieces that join. Also drill holes using a large bit that the screw will slide through in the tray, remove bit and insert toothpick to remember where, then use smaller bit to finish the hole in the post.  Wood is very hard!