Most of the apps I see are pretty uninspired. This looks interesting, novel, and useful. I keep hearing how tough the app store is, but if you actually "make something people want" is that really true?
Some of these games are highly polished, and to compete against them when they're available for free (even for 1 day) must put significant downward pressure on pricing for other games.
Unless I'm looking for a specific game experience (e.g., I bought Beneath a Steel Sky), I'm more than willing to wait for free games to come along to satisfy my mobile gaming fix.
Most people rely on the AppStore for the latter; I think there are more interesting models that people haven't exploited yet.