I've told you why you should upgrade your Adobe Reader, as well as why you need to set Reader as your default PDF viewer in your Web browser.
It's best to do so since using Adobe to view PDF forms ensures you're able to make use of all the functionality that may be programmed into those forms.
This isn't the case when you open the same forms using an iPad, however. There are several PDF apps available for iPads—including free Adobe Reader—but one app stands out since it offers superior functionality.
It's called the PDF Expert by Readdle and the most recent version is 4.5.1. Every update of this app has brought functionality that is simply not offered by other iPad PDF viewers on the market.
Using PDF Expert, signature fields open up to the size of the iPad surface. They then shrink back into the document after you've signed with your finger or stylus. This signature can be saved for future use.
Further, the app allows PDF forms to be saved as flattened files. These are like scanned images of completed forms, where the field content and signatures become part of the document. The form fields are eliminated, however, which is the perfect solution if you're trying to go paperless for clients.
If you use an iPad to fill out PDF forms, checking out the PDF Expert will help you deal more effectively with documents.