Advantages:
-Easy to understand.
-Easy and quick to set up.

Disadvantages:
-There's no mechanism to have partial successes (e.g. you survive the fight but take damage).
-It's puts a lot of decision-making and judgement calls on the DM, almost as much as freeform RP. This means more stress for the DM, and a higher minimum quality for the DM.

The first disadvantage can probably be dealt with (and you probably should); the second is intrinsic, so this will end up as a sort of hybrid position between a normal RPG and freeform RP.