well i advise you the "free versioN"
but let me explain:
you dont have a level builder! well you dont need one ^^! if you have a verry good programm like teragen or 3 studio max, you can make your own levels! Its harder,to use the free version because you dont know where to place objects exactly! but with makign a programm which gives you coordinates of models,you can do it in the executed programm you made
MED is junk! Dont get it! its not worth buying "with" it! 3d studio max or blender or maja has 100% more abilities and freedom than MED!
The scripting Editor is included in the free version ^^
The only thing which could be bothering is,that features like physics or something(dont know really what) but they dont function!
for people with no money PERFECT!