Easy to assemble by myself. All three cats love it, lots of levels, and they immeditately were attracted to it, and climbling and scratching on it, even before it was completely assembled.  3 weeks in they are still as facinated as day one and use it for scratching and climbing, they love the hanging toys, it is very sturdy, even with 2 psycho teenage kittens on it at once.  I looked at many models before choosing this one and feel confident that I made the right choice.