Let me present to you my son Viktor:
He is the harshest software critic that I have ever met. You think people like Ben Brooks are picky? They are nothing in comparison to Viktor.
He lives in a household where there are has always been at least one iPhone and over time we've amassed more iOS devices. As such, when he was around a year and a half old we started to on some occasions let him (under supervision) play with some various iOS apps.
While he thought it was really fun to play with them he did not have the patience for most things and at the time what mostly worked was instrument apps and as at that time we only had my iPhone I was a bit too afraid of my iPhone 4 breaking as it is made of glass after all.
In 2011 I got an iPad 2 from work, and I did on various occasions around the time let Viktor again play with apps for kids, and he did like a lot of the apps that we played with, but as I didn't have a lot of knowledge about what apps were actually good, and he would get really annoyed at bad apps it was hard for me to really keep up, and as such we kind of stopped it for 6 months until sometime around October/November this year.
That was the time when my wife got an iPhone. Previously she had used "feature phones" and one really terrible super-cheap Samsung Android phone, so this was her first smartphone where you could really get apps.
This meant that she quickly got pushed into that period where you are first discovering the app store and where you really want to try a lot of apps to see what is out there. While I am more jaded as I've had access to iOS for years and it takes quite a bit for an app to seem interesting enough for me to try it she was much more open to testing new things.
This meant that she would also download kid apps and let Viktor play with them to mixed results. Some apps he liked, some apps he got incredibly frustrated with. If anything in the UI is unclear and he needs help with getting anywhere too often he would just go "close this, I want that other thing that I like".
My wife actually got really into the apps for kids, she even went so far as to reading blogs and other websites doing reviews of apps to find good ones, and the recommended ones were of varying quality.
We pretty quickly learned that if Viktor gets stuck anywhere more than once he will pretty much just want to close out an app and go back to one he really enjoys.
This definitely swings the other way as well, there is an app called Radioapan - banankalas! which he absolutely adores. He could play with it for hours and it has even gone so far that he will sometimes on weekends come into our bedroom in the morning yelling "Radioapan! Radioapan!", grab my wife's phone and start playing.
As someone who has been involved in a lot of application design processes it's actually been incredibly interesting to watch him use it. Essentially it's one of those apps where he has not ever really gotten stuck, where the interaction is built to train you into what to do. Sure, there have been times when one of the mini-games has been too hard for him, and he's had to back out to do something else in the app for a while, but eventually as he's learned how the app works he has learned how to do absolutely everything in it.
This from a kid who has gotten frustrated at some apps because he hasn't been able to figure out some navigation thing and wanted to close them out within minutes of starting.
So, what can we learn from this? Well, mainly that kids are definitely the harshest critics, but they know good interaction design when they see it.
We also learn that there is nothing wrong with educating users on how to use your app as they use it, but you have to make it really intuitive for it to come across and don't try to teach users too much all at once. Dropping the screenful of text at the start of an app or a slideshow of images with 20 arrows will not even work to educate me into using your app, it just feels like you're not even trying. Make the most crucial things really obvious and then educate me about other things as time passes.
In general I'm also a critic of bad interaction design. Apps that feel really strange or clunky to use I will uninstall and go looking for better alternatives, and while my patience is usually far longer than Viktor's I've noticed that I will remember early signs of bad interaction design all through my usage. Even though I won't completely dismiss an app as quickly first impressions count, and my patience gets lowered by the same things on some level.
While he doesn't quite yet have the understanding to really get something like a calendaring application and what to use it for I think his way of approaching user experience is still valid, hence I try to always keep it in mind myself.
I guess what I am trying to say is, bring out your inner 3-year-old when doing interaction design, it will lead to things that make more sense for users of all ages.