Super easy to assemble- took me less than 30 minutes by myself, with two excited toddlers trying to help!
A lot of other reviews noted that there were not pre-drilled holes- this is actually how it is designed per the manual. I lightly hammered the screws in their marked spots to get them started and then used a power drill to screw them through the plastic. I did not need to pre-drill anything. My kids absolutely love the slide and the activity on the side with the balls and basin.