Several portions of the right shoe upper have separated from insole, either due to poor workmanship or failed glue. A few pairs of socks have been stained by the shoes, normal wash (machine wash with detergent) couldn't remove the stains on the socks. That's it and now I am returning them.

The shoes are light and comfortable.  There are visible glues on the insoles which are not good signs; one can check the product image to find out.