Easy to assemble. Very clear pictorial instructions. Also included spare screws and extra hanging ball without bell (my boy hates bells so have changed that). Only issue is stability, but expect all cat trees have similar problem - other smaller cat tree I have does. Have had to put books on base board and tightly attach strap. Suspect I may need to bracket it to wall, as my boy loves jumping up to mid and top heights rather than using levels, so need more stability than for some cats (hence no reduction in star rating). And it is big - can just get away with it in my not-so-big living room!