Assembly was ok. The directions are a little hard to follow, so I just went off of the picture on the box. It is a little flimsy, but my daughter likes taking things apart anyway. It's part of the fun for her. She has a lot of fun playing with it. It was on sale when I bought it though, so I don't know that I can say it's worth it at regular price.
I bought this for my nephew. He loves it. It is a bit flimsy in construction and the directions are ridiculously small and fairly hard to decipher but overall a good purchase. He uses all kinds of cars on it.
The setup on this toy is not stable. We have other Smart Wheel setups that are much better. This was a complete waste of money. We threw it away because we were tired of having to 'fix it' all the time.