In case you thought that it only takes a black mock turtleneck and an over-produced demo video to succeed, it apparently also takes not-so-subtle attacks on developers of pre-existing apps.
Small and dirty iOS demo showing NSLinguisticTagger live-detecting sentence structure in an UITextView.
But maybe it's best to just let the market decide.
Any way, consider this my review of Writer Pro. Sorry, no affiliate links.