I have tried it a few times. It's good if you're new to the game. Otherwise not so much. I found I leveled slower by using it, as it's suggesting to take the longest possible route usually. Basically following roads everytime, when you could take an easy shortcut. Especially if the shortcut involves a bit of fall damage, it's out of question. The "go here" spots don't also update if you take a shortcut, and then the waypoint arrow points to wrong direction. But perhaps it has been updated since then.
Dugis Ultimate world of WarCraft Guide installation is not impossible, nor should it deter you from using another guide; remember many are very satisfied with Dugis Guide. However in order to install Dugi’s WoW leveling guide you have to download their installer, you have to download each part of their guide individually (about 16 files). Once you have all the installation setup files and the installer in the same folder, you execute the installers. All the installer does is UnZip each file & place it in your Addons folder. The process is very similar for the Macintosh.
On March 23, 2018, Zygor Guides announced that they would end support for their ESO guide. Later, via answers given on the forums, they confirmed they would not add a leveling guide for Summerset. Their guide is Public Domain with Zygor's blessing for the community to create guides. So I took it upon myself to create a Summerset guide for the ESO community.