RAD Tools for Cross Platform Mobile and Desktop Development. Is it for real?

So called Cross/Multi – Platform RAD tools for developing mobile and sometimes desktop apps keep popping up faster than I can keep up with.

Usually they have some custom scripting language you need to use to produce your programs, some use JavaScript/ECMA Script.

Some products claim to produce  produces native-like performance applications while others make HTML5 “apps” or anything in between

Personally I’ve never used any of these, but I’m wondering what the general feeling for these tools are, from a professional angle of view.
Tools like RunRev’s Open Source LiveCode is one example. It has a growing community, and looks pretty polished.
They also give out a free version for personal use.


There is also MoSync which lets you use C++ and claim to support nine (9!) platform from the same code base.
It is Open Source and free (as in beer and freedom).

Also there is PhoneGap, Appcelerator among others…
So, have any of you had any experience using any of these tools? Are they here to stay or go?

I’m not sure what to think.

It’s cool that they give anyone with a computer and IQ < 50 the ability to create applications, but is the final product worth anything?
Does it produce efficient code, and if so, why are they not more widespread in use?

Please comment if you know more about these tools than I do. That should include just about everyone!