Pretty awesome if you ask me
I have no use for Visio integration/compatibility, so I can speak to those features of this app. What I can say is that Omnigraffle is a really solid vector diagramming app on both the iPhone and iPad. It isnt quite as easy to use as the desktop app, but then again you are using your fingertip instead of a mouse pointer to position elements. The fact that I can even consider content creation on an iPhone is an indication (to me) that Omnigraffle has a hit with this app. Bottom line - if you have reasonable expectations then I think youll be pleased with Omnigraffle on iOS.
smc289 about
OmniGraffle 2