These chairs assemble quickly - just screw on the legs and slide the back on.  There is no locking mechanism to hold the back on though so if you grab the back to move the chair, it can slide off.  As far as comfort goes, they are very firm. The leather is also isn't as soft as we prefer but overall it's okay.  We purchased these on sale for almost 1/3 off the normal price which is why I'd say these were a good purchase.  I would not pay full price for these chairs, though. They do look nice in our room, though.