There is so much, I can't remember of what is all new in A:M v16 compared to v12.
Be aware, that since v13 A:M is using a new structure in its model-files (and others too, including the Plugin-files, if I am not wrong), so that you can import v12 files to v16 (never had any problems with that), but you can't import v16-files to v12.
FastAO is a new and very useful plugin available from v15 on. It simulates Ambient Occlusion very fast.
But since you not even got AO in v12 (I think it was introduced in v13, so I am not sure)...
Was 3dPainter available for v12? I am not sure... it is a nice programm that can be bought additional to A:M which gives you 3d-painting-possibilities...
Facial Motion Capture is possible by using A:M Track, another nice programm.
Beside the pluginsThere is SSS, AO, IBL, Multicore-support (to a certain amount), a new 64bit-version, Netrenderer, Fluid-Particles, Newton Dynamics, an NLE, OpenEXR-support, A:M Composite, STL-Export, DirectX-Export, countless bugfixes, better hair-particle-shaders (you've got the hair-system, right? think it was introduced in A:M v11), some very useful new shaders, support for 3dconnexions 3d-controllers, and so much more, I cant really remember all of the new features.
v12 > v16? You will never ever regrad that.
See you
*Fuchur*