Monkey the language in many ways is like a basic version of Java or C++. It is Object oriented out of the box.
It's only good decent quality IMO is that you can convert code from Monkey into different platforms native code. In other words you could build monkey code and translate it to X Code for ios devices and you can then add on stuff by yourself in xcode like iAds.
However, it is missing a lot and only comes with the bare bones basic things. According to Mark no major features are expected until after April 2012. Only small updates and bug fixes.
o No physics support (you have to create it yourself)
o No networking support
o No virtual joystick support (you have to build your own)
o The IDE is very simple. The IDE is really just too simple
o No built in way to do collisions (you have to build your own)
o No multidimensional arrays
o Poor documentation (horrible and very basic)
o Has issues with speed on many platforms (speed can be a big issue)
I could go on and on, but I will stop there. Mark (the creator of Monkey) basically leaves it up to the community to fill in the gaps. Which for $120 is not good.
That is my perspective on what Monkey is all about, of course monkey does support more platforms at the moment, but HTML5 is just too slow and unusable.
Yes, you can make games with Monkey, but a lot of the work you have to do yourself. So, honestly for gaming it's not that great for $120 US dollars, that is kind of expensive for what you get.
App Game Kit (A.G.K.) - Want to be creative on many platforms at once? This is the tool you need.