Bought Tier 3 of YouBooks. Got great help for their support team. The AI model actually took the time to do the work. No rush to push junk out. I encourage a few over the shoulder videos to help me learn to use all the features. I think it is a great product. I am a premium+ user of Grok3, premium user of Perplexity and ChatGPT. Youbooks does a better job than any of these. Youbooks does some sort of iterative, or step by step review of the book you are working and then gives a ton of useful information. I am looking forward to using it to assist me in my educational design work.