How much functionality is actually left in iPDFs?

Definitely 2nding what James said.

I wouldn't necessarily say that there's little interactivity left in PDFs, it's more like there never was much to begin with!

Some key points:

Re: audio/video, the problem is the player. It's not possible at this time to tell a PDF which player to use for the A/V file. So one solution we use is to embed not the A/V clip but rather a clip/frame of it that when clicked, takes the user to a website where the A/V clip will play. As James said, the web industry has now figured out how to make A/V be fairly universal and flawless across platforms and browsers.

... However when I take an exported iPDF and open it in a browser, it starts having issues, same thing goes for PDF readers that aren't Adobe based, I can't account for what will and wont work outside of a controlled environment.
By @ConnectionFailure

In order to open, read, and interact with a PDF file, the user needs to have a PDF reader utility, something like Adobe Acrobat Reader or full Acrobat or any of the hundreds of off-brands on the market. These readers must follow and conform to the ISO PDF Standards (ISO 32000 and possibly others) so that they recognize the various programming details and render/process them according to the standards.

All of that techno-babble doesn't happen in a cheap little browser. Only within the past 18 months have any of the browsers begun to address PDF requirements and start to render them. But those that do only process the bare-bones features, such as rendering text and graphics. These advanced features aren't available yet:

• Interfactive forms.
• Accessibility including all of the possible PDF toolbars and panels.
• Hyperlinks.
• and A/V.

Don't hold your breath for this to happen: even the essential primitive PDF features have taken 30+ years for the browser manufacturers to address.

And then there's the ISO PDF standards. A/V has been "refined" in PDF 2.0, but I haven't seen it being used yet.

So as both @BobLevine Bob and James @James Gifford—NitroPress  commented, just so "no" to interactive anything in PDF. It's value is that it produces a static snapshot in time, not something with interactivity.

I wrote this EIGHT YEARS AGO and things have only gotten worse.

It's okay to say no to interactive PDF (boblevine.us)

>So my two questions for you guys is do you think iPDFs are a valid offering to clients?

No. In no way.

>If so, what interactive features will actually function cross platform (consistent through different PDF readers & browsers alike)

See first answer, but if you do use it: simple links and variations of links. Nothing else: not buttons, not Object States, no animations... almost nothing.

Don't use it for anything else than link orientated stuff (TOC, Index, Weblinks, Cross refs or pages as link goal)

PDFs are very nearly the perfect solution for sharing documents, highly formatted or not, as long as interactivity is limited to navigation links.

There isn't any really good, highly interactive format other than HTML. Everything else was limited from the start, is dependent on a single host/source point, or is dependent on a reader/app being compliant enough to standards to support advanced features.

It's all very much a case where the industry need/ed/s to get its act together (literally) and support one good option among themselves, but between Tandyism (trying to keep a platform and market share exclusive) and sharing of watered-down standards with no enforcing body, we're left with a bunch of weak, limited solutions that remind me of the old shareware caveat: "This software is guaranteed to work perfectly on my [the developer's] system."

In retrospect, I find it nearly miraculous that the web world overcame its era of this, settled on HTML5/CSS3 and now has almost universal support for both consistent rendering and the full range of advanced features.

Here's to _______, the content, rendering and animation standard that will sweep away all the half-stuff the way it was done for web. Just don't hold your breath waiting for the name.