Working alone, I took about 2.5 hours to assemble the bunk bed, working steadily and methodically following the instructions. First, arrange the pieces carefully so you use the correct ones in the correct place. Some of them look very similar, but because of holes for fittings, they are not. These are all lettered, and the letters relate to the parts indicated on the instructions. Similarly, identify the bolts carefully, as these are different sizes, with some very similar.
I made one mistake in fitting the bottom bed frame the wrong way round, but it wasn't too difficult to remove it and turn round.
Minor quibbles, hence the loss of a star: first, the manufacturer's packaging was pretty good but not 100%. One of the pre welded brackets for the top bed rail was bent, though it wasn't difficult to straighten. Also there were one or two dents and marks in the paint work, enough to take the shine off a new product, but not enough to make a big deal and send it back.
Second, the bolts supporting the ladder were a tad too long, and a couple of them, even when tightened fully, were still loose. I solved the problem by adding washers to make up the difference, but of course I shouldn't have had to.
Once assembled it felt very solid, and is probably fine free standing, but not wanting to take any chances with my grand children I decided to secure it to the wall. This I did with a couple of water pipe brackets around the top safety frame. It's added that extra bit of stability so when I (68 kilos) climb the ladder, there's no movement. And they're hidden by the mattress.
All in all, I'm very pleased with the product, and actually, the instructions must have been pretty good, because there was not a single a blue air moment during assembly, probably a first for me!