Have been using this as I work on the go and bringing a stand is not possible in my situation. There's not always a guitar stand available, so putting this in my laptop or guitar bag is a lifesaver. Most desks are perfect height for this and when there's a carpet on the floor there's no need to worry.
Just watch out when leaving cables plugged in. You might trip over them and still let the guitar fall.
Edit:
I started disliking and using the product less. It doesn't feel as safe as you aren't always sure that the height is good for the guitar you have with you, and if the desk has a small angled edge, it doesn't work.
D'addario also has a product called the Guitar Dock (PW-GD-01) which is this thing with all the issues solved. It's more expensive though and isn't something you can throw in any gig bag, so still have these rests in a couple gig bags just in case.