Although Apple is pushing EPUB as the de facto standard for their new iBooks app, there will be plenty of times when you need to open and read a PDF file that’s not attached to an e-mail. ReaddleDocs is one of the classic iPhone apps which does that — and a whole lot more — and it’s now available for the iPad.

Practically a legend in the iPhone world, ReaddleDocs for iPad was fortunate enough to be one of the first wave of apps to hit late last week, just in time for the new device’s launch day. If you aren’t familiar with the version for the iPhone or iPod touch, don’t worry — even though there is now a separate version for the iPad, the feature set retains parity with the diminutive edition, but the extra real estate the iPad screen brings to the table is well worth a double dip at the App Store.

First and foremost, ReaddleDocs is a premium PDF viewer. In addition to handling large PDFs with ease, it supports full text search, text reflow, PDF links and outlines, password-protected documents and it can even extract text from your PDF files. If you already have a virtual library of e-books in PDF format, you won’t be disappointed in using ReaddleDocs to read them.

But PDF viewing only begins to scratch the surface: You can connect your Mac or PC and copy files to ReaddleDocs over Wi-Fi (or even via EDGE or a 3G connection thanks to the Readdle Storage website), e-mail files to friends (or even transfer documents between iPads), read Microsoft Office documents and save e-mail attachments or even files from the web.

If you’re a frequent user of MobileMe’s iDisk, Dropbox, Google Docs or other such services, don’t worry: You’re covered, too. You can easily connect to these popular services as well as any WebDAV server in order to transfer files with ease.

Finally, ReaddleDocs isn’t simply a document viewer — you can copy videos, photos and much more to the app and play them without having to leave ReaddleDocs. In fact, we copied a 720p HD MP4 movie straight to the app and it played beautifully, without having to add it to iTunes and sync our device.

Thankfully, the ReaddleDocs for iPad experience is just as excellent as the one on the iPhone or iPod touch, and probably even better, thanks to the iPad’s larger screen. On the left side of the screen are five options which, when selected, open on the right side of the display. Documents holds whatever you throw at the app, and you can create as many of your own folders inside there as you’d like. The Documents folder is also what appears on your desktop when you use Wi-Fi to connect to the app.

Network is a pane that connects you with the rest of the world, including files you have uploaded to Readdle Storage as well as MobileMe iDisk, Dropbox, Google Docs, Box.net and other WebDAV servers. Browser offers a full-featured version of Mobile Safari, with the addition of being able to download files, which Apple doesn’t allow. Attachments allows you to login to your e-mail account and download any file attachments directly to ReaddleDocs. Last but not least, there’s a Settings tab which keeps all of your preferences within the app itself.

While it’s a shame that Readdle didn’t make the app universal so that one purchase works with the iPhone, iPod touch and iPad, the $4.99 purchase price for the dedicated iPad app is still well worth the money if you are frequently using your device to access and read documents or other files. ReaddleDocs for iPad version 1.0.0 is a 6.8MB download available now from the App Store for iPad.