As a fairly advanced DIYer I expected to put this together in no time at all, but I was mistaken - it's a pretty big project and will probably take 10-20 hours depending on your experience level. After building this I have some tips that may help:
* Several parts look extremely similar but have slight differences, and it's not obvious which part is which (they're not labeled). The instructions include a Parts Identifier that makes it easier to distinguish each part, but for some reason that section is in the middle of the instructions after section 3. I wish Lifetime would just label the parts with their part numbers, but since they don't you should use the Parts Identifier to make sure you don't get the parts mixed up.
* Use the BILT app, which gives 3D versions of each step. There were a few steps in the instructions that were not completely clear to me, but every time this happened the BILT app helped me figure out what to do.
* The barrel nuts (part BTS) and their matching bolts are extremely prone to cross-threading. If you start putting these together and notice a lot of resistance, take the bolt out and start over. If you try to force it you can shear off the bolt inside the nut, and then you'll have to wait for spare parts before you can finish putting it together. Fortunately Lifetime customer service is great and shipped out the replacement parts to me at no cost, no questions asked.
* There are several sections where you have to use self-drilling screws to make holes in metal. The instructions tell you to just do this with a screwdriver, which I guess is technically possible but it will take forever. I would highly recommend using a center punch and hammer to get this started, then a small drill bit (I used 1/8-inch) to make a pilot hole. Once you do that the self-drilling screws will go in MUCH more easily.
* If you think you can do this alone you're mistaken. Several sections can be done alone, but unless you have four arms you absolutely need a helper for some of the other sections.
* A ratcheting socket wrench will make your life a lot easier. A deep socket (not regular socket) that's 1/2-inch makes it much easier to attach the steering wheel.
* There were a couple of sections where I found a right-angle drill adapter to be very helpful. I'm pretty sure you could get by without one, but it will make things easier.
Overall I have no major complaints about this playset, I just wish that all of the parts would be labeled with their part numbers. Delivery was easy, assembly was time-consuming but not overly challenging, and my kids love it.