These all have widget systems and GUI tools to create apps fast. Initially, making a cross-platform app seems easy and simple. It turns out debugging is really, really hard. There are many layers and a ton of version/device fragmentation. Betting my dev money on it for professional apps doesn't seem like a great idea. I think the killer feature should boil down to this:
Magikai is great for kids who are just starting out in programming
EDIT: And more -- http://dailytekk.com/2012/04/02/100-tools-to-develop-a-kille...
Generally a decent programmer will hit the limits of the 'easy' framework just slow enough to have wasted a ton of time. Then you have to drop into native code to fix the bugs that are not the priority of that specific framework.
Appcelerator has gained so much traction because they have a ton of developers concentrated on bugfixes and full native API support.
But, to get children started on programming is always a great idea, and as all of us young devs grow we will want to share the dev experience with our kids. If they can make that possible I think they'll have a home run on their hands.
This is worth repeating. Kids are, in general, fabulously creative and completely open minded with new technology. I can see all sorts of fun, frivolous, nefarious and downright evil uses for a simple app maker that works on any kid's phone. Little Johnny makes a simple set of static pages that stores crib notes for his classes. Evil Britney, who has a few more coding chops, comes up with an app that screen-scrapes the yearbook site and lets her friends rate all the boys in her year (she got the idea from The Social Network.)
If these guys can get their teeth into that market either officially (through schools) or via the terrifyingly powerful playground word-of-mouth network, this could become quite big. It's a hell of a long shot though.
None of the other frameworks I am aware of even consider kids as a target market.
Magikai may only be useful for people who really have a basic understanding of html and want to create a simple app that they have been thinking of.
But not my cup of tea.
It infuriates me to no end.
For my part, I'm a bit scared of web development: without a compiler, I'd have to keep working all the time. I'd miss fencing on chairs.
It doesn't come near compiler times, but it's close enough.
I don't consider any of those kits very easy to deal with, despite the fact that I am fully capable of building apps with them.
They're certainly nowhere near the realm of kits like RealStudio/RealBasic, FileMaker, Access, VB4/5/6 or even WinForms with Visual Studio (some of which I know are not cross-platform...but they are easy).