The first points in the Guide deal with the general issue of misrepresentations. And although the language in the Guide is chatty, the points in there are all business. But they're also not hard to comply with, boiling down to one simple one: don't say things about your app that you can't prove to be true. This seems like common sense. Amazingly it's not. The FTC points to an app whose developers claimed it could cure acne. I'm not even sure how that could be possible. Apparently the FTC agreed, because they took action to shut it down.
But that much is easy. Where it gets a bit more involved is when the FTC turns its attention to privacy issues. The FTC is very concerned about privacy in the mobile app space. I'm even told they have mystery shoppers downloading apps and testing them out for privacy compliance issues. No surprise then that most of the Guide is dedicated to privacy. And the Guide contains three additional big points on privacy issues that app developers should consider:
Speaking broadly, it's against the law in Europe for you to have users in Europe and keep their personal data in the USA unless you've agreed to abide by a set of rules called the Safe Harbor rules. These rules basically say that you'll give European users all the same protections for their personal information that they would have if you were in Europe. I've linked to a pretty good summary below.
You might think this isn't relevant to you: you don't live in Europe, you're not planning to open an office there, and so you shouldn't be subject to their laws. Maybe. But if you think you're ever going to have an app sold by iTunes or Amazon or Google in Europe, you'll need to make sure you're paying attention to these rules.
This Guide isn't a regulation. It doesn't give the FTC any new powers or create any new rules. From reading it I can tell it's the kind of thing that the FTC would basically think is just common sense. But from reviewing some of the notifications I get when downloading apps, I can also tell that many app developers wouldn't agree. Only one of these positions can be right. But with the FTC rediscovering that it can bring enforcement actions and showing that it has an appetite for them (see: Apple e-books litigation), app developers would be wise to pay attention.
FTC guide to promoting mobile apps
Safe Harbor basic information page from Wikipedia