Yes this talent (getting AP when killing an enemy) is very strong.
Problem is that it's either 1 or 2 ap for spells (maybe 3 ?). You won't be able as in DOS 1 to make him 3 AP 5 AP that would be 1,5 or 2,5 AP.
I remember loving the fact I had a character that had like 20 AP in his turn in DOS1, he felt like he was a really swift assassin !