It's actually a very friendly programming envioriment. It accepts C/C++ scripts and just about any NDS library I can think of. Although it's limiting at times, it's also keen on grabbing a newbie by the hand and allows to get good effects using pre-defined Actions instead of any actual code until "you know what's going on" and then it's all cake. In essence, if you understand plain english, you'll be able to program in DSGM5 to some extent. Then it's all about learning proper code and dedication.

Darn it, I just finished Portal in my preparations for playing Portal 2 and I've got cake on my mind all the time. >>;