So far the Flying Bundle has had two bundles so far, with moderate success. You can say that none of the games were must-buys, and the bundle didn't have the best pricing, but I can give kudos to 2 specific aspects.
First off, the bundles had a nice variety of games, ranging from your casual games to more hardcore games, with both games on Steam and Desura.
The other aspect is the mechanic of checking off which keys were used. The flying bundle uses a simple check box mechanic to indicate whether the key was used. Once checked off, the buyer can return to the game redemption section and easily tell which keys were used based on which boxes had checks.
I feel like IndieGameStand and frankly and many bundles that use key redemption methods should think about implementing a used key checking mechanic, which can be as simple as placing a check box right next the key to check off once used.
Overall, I am pleased with the Flying Bundle and look forward to its future features.