We've covered PDF Expert a bit before, but this week they rolled out a 3.0 update that greatly enhances the functionality in the app. When the iPad debuted, one of the first apps to rocket to the top of the charts was GoodReader, and with good reason: it was a better PDF reader than Apple's built-in iBooks app. GoodReader wasn't perfect, and hasn't evolved that much. I bought GoodReader and used it for a long time until I had a chance to use PDF Expert. Now I'm sold: PDF Expert is likely the ultimate iOS PDF app out there right now.
Even if you're just reading PDFs, PDF Expert has an edge. I found it caches large PDF files effectively, so swiping through pages isn't an exercise in futility. The responsiveness of the app has to be experienced, it's just that good. New to 3.0 is a Recents button, so recently-used PDFs appear in a shortened list, handy when you're flipping around in different documents.
PDF Expert has had support for some bookmarking in the past, but 3.0 has a full range of tools for highlights and marking within your documents. Plus, if you want to delete all the marks, it's a one-button process. Add to that a full range of document editing tools, allowing you to move pages, insert blanks, copy and paste, rotate and more and you'll see why I don't even think about Adobe Acrobat Pro any more.
PDF Expert already supported forms, hyperlinks and added signatures (a really, really awesome feature which allows you to sign with your finger or stylus and save that signature for later use) so the 3.0 additions are like icing on this robust PDF 3-layer cake. If you frequently deal with PDF documents, be they read-only or forms or anything in-between, take a serious look at PDF Expert.
There's a Pro version of PDF Expert available for iPad and iPhone, plus a "free" enterprise version designed for use with a backend solution from Readdle. If you're in the market for a full business solution, the Enterprise version offers additional features like group sharing options.