Love all the functionality of this app, it's excellent except for one (important, though I'm hoping easy to fix) flaw: the "clap" (both beep and flash) is too long and takes multiple frames of video, especially if you shoot at a higher frame rate. This makes synchronization of audio and video impossible, which is precisely what a clapboard is supposed to do! (true, this app is called "slate", not clapboard, although it has both features, and it's a pity that one of them is unusable).
With the clap/synchronization feature unusable, I can only use this app as a slate that displays information (very useful in itself), but then I need to use a second app for the clap which is awkward and a bit ridiculous.
Take a look at Auto Clap, another free app, which allows the duration of the clap to be set to as little as 10 milliseconds - if you can set both the light flash and the beep sound to 10ms (allowing variable duration like Auto Clap does would be even better), you will have a true, fully functional slate/clapboard and the eternal gratitude of many filmmakers (and my 5 stars).
With anticipated thanks