Once you get the arms on, the rest of the assembly goes quickly.  I'm a 65 yo female and it took me about 2.5 hours.  That is because I kept getting frustrated with the arms and stopping to play candy-crush.  Yes, the seat cushions are firm, but I believe they will soften up.  The back pillows are a bit flat, but since they were vacuum sealed they will fluff up over the next day or so.  Overall I am very happy with this sofa and the price couldn't be beat.