Navigating through the menus feels pretty clunky right now. Part of what contributes to it is inconsistent behavior. At the Battle, Deckbuilder, Daily Quests, and Settings screens, you can click anywhere along the outside to go back to the previous screen. But that doesn’t work on the Solo and Shop screens; you have to actually use the back button on those. The UI could use some extra thought to make sure everything is consistent and that it’s easy to navigate between the most common screens (especially quickly flipping to Deckbuilder from Solo/Battle screens, without having to back out to main menu first).
Edit: Another weird behavior is when you level up while doing Solo quests. After you receive your reward, it takes you back to the main menu instead of back to the quests.