Just tried out "Preview > Preview" on iPad on a new iPad (iPad 3), and it looks like it's lo-res. Is this because it's just previewing? Thanks!
Are you doing the preview from the Folio Builder panel or from the Overlay Creator/Folio Overlay panel?
If you are in Folio Builder then the preview is what you will get on the device. If it looks low-res you should make sure the folio you are previewing is in PDF format, and if you are specifically going to target the new ipad that the folio size is 2048x1536.