I assembled this by myself. It took much longer than 20 minutes but I was attending to a toddler and an infant while assembling. Could have been possible. 
The doors lined up fine I’m not sure why some said they had issues with that. 
Two of the shelves are adjustable. Works great for organizing all our shoes! 
Not super great quality(particle board) but it is a great piece for the price and fulfills it’s intended purpose.