I'm in the middle of this lesson, and I am pleasantly surprised with how it's going. The students seem to be understanding most of what's going on, even with no prior experience in applab.
During lesson 3, I let the kids play around in applab for half a day. I started by letting the kids mess around in design mode. They added buttons and pictures and messed around with various properties. From design mode, we went to events, which made my life easier because I didn't have to walk them through adding the buttons.
One of the main issues that I have run into is on lesson 7. We ran into what felt like a major issue, but actually wasn't. Students tried to use keydown in the event handler, and that didn't work. We needed to use an if statement with event.key == "Enter" but then we did it again today with change, and it worked fine.
I will say that this is a really bad lesson to get half way through on a Friday. Picking it back up on Monday was a chore. I think because several of the later levels aren't as engaging. I almost wish that this level was more project based, so the students are reviewing applab while building an app. For instance, it starts on a home page and goes to an about page. Stage 10 could be a calculator page in the students app. That way students are working towards a full thing, rather than small little exercises that aren't connected.