Chapter 3 went well without issue. It describes how to use the Experience builder and some of the major working parts of it. The widgets made a lot of sense and I liked how they showed so many different and useful ones. I found the UI of the experience builder to be a bit confusing, but I think it was due to something with my perception and not the app itself. I think this is a very versatile tool that will really help with communication and making maps more accessible to non-cartography nerds. I know I really would have appreciated a website like this in middle-school if I had known about it.
Chapter 4 had a lot of good information in it too. It talks about all the uses that mobile devices have in GIS, specifically for surveys, collaborative maps, and AR experiences. I think the surveys are a super useful tool, but I find the editable feature layers the most interesting. I think giving the opportunity to coworkers, partners, or volunteers in the community to work on maps with you is an important tool to be used. However, the downside is that you may have people working on maps in different styles when you need one coherent language.