It works alright, but I feel like there are better options out there. You can easily build, print, save, and share decks, as well as simulate drawing your cards. Be sure to keep up to date on the latest rulings as well as the latest Banned and Restricted list.
The Official Games Workshop FAQs Page includes the latest FAQs for Warhammer underworlds under the Age of Sigmar page.They also have a Twitch channelthat has underworlds stuff on it now and then.The official Underworlds Website has lots of cool painting videos.These have all been helpful to me, so you may like them as well: Official Resources:
Below are some of my favorite places to go for Underworlds info, deck building, and other stuff.