Methinks they should have released these maps for free. They seem like a fun addition to the game, but not worth $10. One of peoples biggest gripes with Mirror's Edge seems to be how short it is, for how much it costs. They had a perfect chance to add something to the game, to increase it's value, but instead, they are making customers pay even more?
Seems to me that they would have gotten a lot more people paying $50 for the game if they saw more value in it, and getting more people interested in the series in the long term (they are planning sequels IIRC), rather than a few people paying $10 for the pack. Even though I loved the game, most people I have talked to just don't think it is worth it.