A lot of Antstream's current games are really niche, and it's not hard to see why they're having to give subscriptions away for free. It's clearly not taken off, and there's lots of proof for this on it's online leaderboards. I played the first level of Bloody Wolf - a reasonably well-regarded arcade game from Data East that's been on the service for more than two years - and it placed me nineteenth in the world.
Still, it's a work in progress, and the newest games that have been added (like Mortal Kombat, PacMania and Earthworm Jim) give me hope that it'll appeal to folk other than weirdos like me.