Yes, you need to learn to code and there is no GUI to speak of. Not really an alternative to GS at this stage... unless you're willing to learn to learn Lua!
Unity is FAR better, and it has everything. In addition it has Drag-n-drop asset management, and very easy scripting (javascript or C#). It cost around $400 one time (not yearly) to put out iPhone, Mac, PC, and WEB applications. Unity also supports xBox 360, Wii, Android, and PS development for additional cost, but at least the features are there and it isn't beta.
You can not only do 2D, you can do 3D with it too.
Before dealing with Corona I would highly recommend having a closer look at the cocos2d framework. It´s not comparable with coding every single graphics stuff etc. with Open GL ES but you have nice stuff wrapped in classes and functions there for direct sprite access, actions, tileset support, particels, box2d integration and what not... It´s not that complicated. When you decide to code at all then I´d suggest: at least give cocos2d a try.
Comments
Also, IMO, the coding doesn't look that hard. In fact, you only need one line of code to load a image, and only a few lines to do physics.
Here is the link to a full online book as well:
http://www.lua.org/pil/
Also no level or map editor.
You can not only do 2D, you can do 3D with it too.