Good thing is primary secondary isolation gap is correct, along with the reflow soldering being good and sufficient for the most part. Trace fuse is there, and it is thin enough that it will fail before any major fireworks occur that might damage the case integrity. Case is a relatively decent mould, though the join area should have had either solvent welding fully around it or some screws to hold it together.
Are you sure it is not a constant current supply, sort of done by accident? Seems like that would be the right thing to drive those cheap light sets which rely on the source impedance to provide current limiting. Universal input as well, you have the right set of pads to handle a US socket spacing as well, and the silkscreen with the reversed numbers and mirrored s as a 2 are nice touches, along with a double sided silkscreen. They actually have 2 earlier revisions of this board? rev 4 will remove 3 diodes and lengthen the wiggly fuse to cover the gap, along with making the traces thinner. Copper is expensive, recover as much as possible from the etchant.