This toy was very delicate to assemble and took an adult several hours to put together with a tiny screwdriver (which it doesn't indicate is needed anywhere and isn't included). Once put together the solar panel does not function unless held immediately and very closely under a light. While I bought this as a silly gift for my boyfriend (who loved the idea of it) and it was fun to assemble (mostly) it isn't the greatest toy and I definitely wouldn't recommend it for young children. I might have rated it higher if the solar panel had actually functioned since the rest of it was a fun design and idea.My 8-year-old and I assembled this together. The experience of working together, following specific instructions and exercising spatial reasoning is fine. I performed the trickier steps to ensure smooth functioning.We live in southern California and have plentiful, strong sunshine. This crab did not perform. Only when angled essentially perpendicular to solar rays did it even move. Then, the resistive forces of friction and gravity were too great for the motor to overcome. On glass, in full midday sun, this crab inched forward a bit and then stopped. Any other normal surface rendered this a plastic crab paperweight.We removed the solar powering unit and built a lighter, less complex robot around it.I purchased this for my grand daughter for Christmas. We had a good time putting it together (it is a bit complicated) but she was fascinated by making it move by shining a flash light on the solar cell. Well worth the price for the benefit of building something with her.My 8 year old daughter assembled this with me. The little sucker was hours of hilarity as her friends helped build obstacle courses for it. It's surprisingly resilient.It's a pretty complex assembly and there's some crucial parts that need to go together just-so. The directions were adequate but required an adults practiced eye to important details. We ordered several kits for the campfire troop and some of the adults found the directions challenging and the kids would have been way over their head.My 8 year old wanted this toy. She saved up her money. I was worried because there were a lot of little pieces. She needed some help with the tiny screws, but otherwise she was able to do this herself. It has held up to everything we've put it through, so far. It's been great to have hands on with solar power and one of it's drawbacks - shade.My 11 year old, not only was able to build this in less than one total hour, but got it to work quite well. The instructions are very easy to follow, and could not be more clear. He had one little hiccup in the construction, by placing a gear the wrong direction, but he was easily able to correct it.He has it running off of a 100 watt bulb currently, due to snow on the ground, but it is running quite fast. He is extremely eager to take it outside as he knows it will run like greased lightning.Purchased because of being solar powered well still getting solar powered but DOESNT WORK!!! Been waiting since January!!!!it works!