Comes fully-assembled (other than the phone holder). As described, it takes up very little space when folded. Our living room feels much bigger now that the X25 has replaced our old walking pad.
Very easy to unfold and fold back as needed. It makes a "snapping" sound when folding/unfolding the last part. You quickly get used to it and it makes the whole setup feel more secure.
The motor is surprisingly quiet at lower speeds, so you can watch TV or listen to music without needing headphones.