I'd like to think that there are 3 main killer features:
1. the visual code editor: this allows you to create interactions that simply aren't possible to recreate in other tools. If you want to see in in action then check out:
2. Real components which can be quickly composed and nested. This allows you to quickly create complex designs that aren't possible in many other tools.
3. Powerful device preview. UX-App will push all changes to all connected devices wherever they are in the world.
Thanks for your question, I'd be thrilled to have you on board with UX-App. Contact me at eli@ux-app.com if you have any further questions.
PS; If you do sign up to UX-App, let me know and I'll upgrade your account for you!
congratulations on launching. even with no other distractions it is no small feat, and with a full-time job and a family it must be even harder.