I have a visceral reaction against nickel-and-diming on the app store this way (buy before you try, in this case for FX) and I don't have any music bought in Spotify or iTunes so I gain nothing from its integrations.
But I ignored that to try it out... the app requires a front-facing camera which my iPad doesn't have. LOL. Guess I'm destined not to try it.
The app seems cool for beginners whose music is in their Spotify or iPad. I think if I were using it, I wouldn't want the fancy animated (and thus slow) FX selection mechanic they seem to have
I was looking them up on Twitter to see if I could report that front facing camera requirement as a bug. Found a really cool use case: One guy was excited he could now DJ at his upcoming camping trip. That kind of mobility is super awesome.
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