I have built quite a few of these buildings and consider them good value for money. Biggest problem I have had is with gaps in the roof sections. Rather than use lots of filler I decided to use faux fur to thatch the roofs, trimmed down fur, attached with Impact adhesive, then washed with diluted PVA glue is just the job for creating neat looking roofs, adding a bit of individuality to the buildings and is an easy job to do.
It was only after struggling with assembling them that I learnt they advise you use a hot glue gun and to stick a wood template between the first three walls to assemble to square things up, I used dowel in all the corners to same effect. End result is a nice strong building.I reinforced the glue gun with fillets of epoxy resin.