It took me an entire day (by myself and only a screwdriver) to assemble, with a few issues, but I finally have it built. My 2 year old son loves it, which is what counts.

I recommend assembling with two people, and a drill. Like others have mentioned, take a good look at the screws and where they should go - the brown-painted ones should go on the outside, but the instructions will not mention this. The picture assembly instructions werent the best, but did allow me to figure it out.