Almost great, but instead kind of terrible. The enemies that come in around 200 seconds are a MASSIVE jump in difficulty. I thought with a good strategy and some luck, I'd be able to keep going. No. And then it wasn't fun, just frustrating.
Good games like this usually have some persistent upgrades; earn a few points each run, and eventually upgrade your way past the wall. If this game had that, it would be a blast. It's slick and polished pretty much otherwise; with persistent upgrades, I'd happily buy it