It took two of us quite some time to build. I suspect that is because I was being extra careful before placing some parts and also I only have a set of steps, rather than step ladder.
I only used the written instructions and these seemed clear and easy to follow. I see that another review mentions an issue with putting the shelves on last and it not being possible. I would advise them to look again as it is actually quite easy to do.
As also mentioned, I would advise using clamps in any place the screws push against plastic. They will make the overall task much less stressful. That said, I quite enjoyed my time putting it up.
I am very pleased with the shed now it is built and it seems very sturdy. However I would be careful about leaning anything heavy against its back wall.
In fact I only have one issue, and that is that I was sent a considerable amount of extra parts - and I definitely built it correctly. In total I received a complete extra roof (including fittings and bars, four side panels (one for a window), two corner panels, and two extra flooring panels. It's more than half of another shed! I wonder if this is common? It will be very difficult to get rid of, and it also seems a great shame to throw it out.