The strong point is definitely some of the creativity and emergent behavior you can get with the different enemy variety. Slowing down a quick guy on a slow guy, or being careful to not trip the aggro range when they spawn in the corner..
I think the random generation and infinite gameplay actually weakens this a bit. Number go up is fun, but I don't really get to explore your gamespace when I'm just idling in a corner waiting for the timer.
I am always glad to see, of course, any game where the timer is not the bad guy! The timer here is refreshing, a chance to score higher and something I look forward to each round.