The assembly is, in principle, without any problems, the included instructions show exactly how the sandbox is assembled.
Something craftsmanship should already bring and also time, I used about 3/4 a day.
At 300x300 two hands are practical, but it is also alone if one takes his time and the boards can be supported - for example, with beverage crate. Who has no flat floor, straightening the soil should not be underestimated - I was alone busy almost 1 1/2 days ...
Pre-drilled boards are not, in my view, that's a good thing - the sandbox will never ever be perfectly straight on the ground and also to be the planks always forgiven anything from manufacturing to construction. Pilot holes would therefore no longer fit with safety and also could keep moisture there.
Importantly, you should pre-drill in any case itself and not just purely screws rotate so (!) - The boards would probably break.
The quality I would describe as proportionate to the price, is for me perfectly fine - can cut in stores should cost more and the transport would not be without. Some recessions are indeed rather damning, I can not confirm that, and that is not the price justice. I had some research and "wertigere" Wooden sandpits are significantly more expensive.
We have to "cover" with orders, these "needs" is not in my view have. At 300x300 it is divided in two, however the two parts are very heavy and can be moved by one person barely - because the two parts still have 300x150, they are very bulky. I had bought a tarpaulin in the aftermath, it can also remove our mini-market - fixed with rubber and ground anchors (eg from noor). However, the plans depend in turn through in the middle and when it rains here collects a small lake ...