Haxe NME is a very powerful open source game and app development platform written in haxe programming language. It can be used for mobile game and app development both but it is more popular for mobile game development.

Advantages

It has a syntax similar to flash. So a lot of flash code can easily be ported on this platform. It can cross compile to many platforms including Android, iOS (iPhone and iPad), Blackberry, Flash, HTML5. So its easier to maintain game main logic by keeping it in one code base. It cross compiles to C (Objective C for iOS) for mobile native apps. That makes the apps perform faster and game size smaller. There is no overhead of interpreter code in the binary. Many other cross platform tools use interpreter based approach. The compiling to Flash is a great feature. Flash may not be as popular as mobile these days, but it gives you an extra distribution channel with single code base. It also support integrating current flash native code. This may be useful for integrating flash ads API (e.g. Mochi Media and MindJolt API) It is open source. So extending it is a possibility. You dont have to depend upon the release cycles of the platform developer which can be big problem for proprietary platforms. There is a good size community using it. It is not hugely popular but it has potential to be the best platform for 2D game development for mobile.

Disadvantages

It is hard to find third party tools for haxe nme. But since it is open source, you can write it yourself. Many times you find something written by community. Sometimes the community written libraries are not that stable but it is better than nothing. And moreover you can fix them as its open source. It does not have too much support for 3D games. I think it is best suited for 2D games. For 3D it may be better to look at alternatives like Unity3D or Unreal game engine.

Haxe have lots of libraries available written by community. It may be a good idea to see if the project you are working on can reuse some of these. This can be a big time saver. You can join NME mailing list and Haxe mailing lists for regular updates on what is happening in these platforms.