I'm concerned weather this "iStencyl" will bring to the table what iOS developers need. I've tried out today Stencylworks for the first time, and I must say it brings a "Gamemaker" sort of atmosphere. Gamemaker let you build complex games easily with a simple drag & drop interface. Even YoYoGames (The people who made Gamemaker) are looking to producing a version of gamemaker called "Gamemaker studio" which allows you to export your games to not only .exe, but also android, iOS, HTML5 and so forth.
Now, this is what Stencyl is doing, making iStencyl for iOS development. But I fear that it may not come into a reality for one reason, performance. When Adobe started work on Adobe AIR (allowing people using Flash Professional to export their projects to iOS) there were horrible performance issues, and alot of features were cut out (retina display, iPad, and alot of native options).
Now, after a year and a half, they've finally fixed all of their issues. MASSIVE strides in performance were accomplished, and they fixed all issues regarding "not being able to access native API's" with Native Extensions. Allowing anyone to develop an extention needed when a native API wasn't already available directly from Adobe.
To sum it all up, I doubt that iStencyl will have the same performance and compatibility as a work environment such as a Flash IDE. After all, it is specifically designed for games (which is great and all), and I do wish you all the best, but make sure that the biggest issue (performance), woun't be one.
P.S: I would be interested in seeing how well the performance is with apps compiled with iStencyl (number of moving objects on screen, physics, etc.)
Make sure when you finish iStencyl, that you let the developers take FULL control of the environment, don't hold anything back!