I really like feature-flag releases, but they are not without disadvantages.

The one that comes to mind is complexity. Ten features is a thousand possible configurations of your application. Thirty features is one billion possible feature sets for your app.

Ideally, features are independent of each other and work regardless of the enabled/disabled state of the other features. But ideally code doesn't have bugs.

All in all, I think feature flags are great. I just prefer to limit them to the larger, more risky changes.