I mainly use Monokote and have had good results, but I also I have used Ultracote with good results. Ultracote is definitely more forgiving and easier to work with were as Monokote takes more time and technique to apply. The advantages of Monokote are the seams don't pull, the seams are not as noticeable, Monokote is more opaque, and Monokote just has a nicer look. Ultracote is much faster to apply, I would say it takes twice as long to apply Monokote vs Ultracote. Monokote requires heating, shrinking and pulling for a tight wrinkle free finish. Utlracote just requires you to put it on then shrink nice and tight. I just finished my Herr Pt-17 with Monokote and the fuselage was covered with only 2 pieces of Monokote but it took a lot of stretching and pulling. The wings are covered with one piece of Monokote on the bottom and one piece on top. Monokote is a great product but it is a shame that Top Flite will not address its customers complaints. I know that most builders I fly with are using Ultracote and my LHS are carrying less and less Monokote and more Ultracote. I like the ability to just drive down to my LHS to buy covering, so if they get rid of Monokote, I might have to switch over to Ultracote.
I wonder how the builders of Great Planes ARFs apply their Monokote? The Great Planes ARF's I have seen look great.