Not talking about your photos here but in general I am always disappointed with fake Polaroids whether they be on phones or on the computer. It appears to me that the people who write the software have not looked at a Polaroid photo in years (if ever).
But as fakes go, this app is not too hideous – at least there is no vignette or thumbprint on the fake Polaroids.
Full disclosure: I shoot actual Polaroid film regularly so I am biased.