Instant oats make an excellent adjunct for some beer styles, but I don't think a beer using oats as the primary fermentable would taste very good. You'd still need to mash it with plenty of six-row barley to get it to convert. It just sounds like it would be bland, maybe a bit astringent and chalky.
The Fiesty(sic) Goat Brewery est. 2007 & Clusterfuggle Experimental Ales est. 2009
Primary: Saison, Berliner Weisse, sLambic I, sLambic II, IPA, 70/-
Secondary: Orange Blossom Mead, Flanders Red I
Kegged: Fat Man Porter w/ 1469, Fat Man Porter w/ 005, Centennial Falcon w/ Conan, Centennial Falcon w/ Denny's, Barrel-aged Fat Man Porter, Belgian Dark Strong, Dark Mild