Assembly: Not much to assemble, pretty easy logic. The side panels were difficult to set right and to remove, but with some manpower it is manageable.
Function: The couch has a light, elegant design, perfect for smaller rooms, and looked just great. I also appreciated the possibility to remove the sides if needed. So if you are looking for a sitting couch for a smaller room - this is a great option.
However, this Sofa is NOT MADE FOR SLEEPING. I have tried to sleep on it and it is pretty uncomfortable. We planned to use this couch for guests as a sleeping place but being merciful to their backs we returned it. The sofa is too small for sleeping in all directions and uneven. As the sleeping surface was not in the product description, I just summed up the sit and the back dimensions and assumed this would be the sleeping area - nope, wrong assumption. 
Return: the Sofa was picked up with no costs for us, the return was fast and unproblematic.