MobileStudio requires FTP, and I wasn't in the mood to drop more cash on AirSharing Pro as I've already spent way too much on apps. I also tried MyPDFs and iPDF but felt they were too limited and rushed to be useful to me. GoodReader, however, hits the spot as a wonderful and capable PDF reader. Plus, it'll read text, image, audio and video files and anything that can be opened by Safari. I'm using GoodReader to manage some big PDF files, upwards of 200MB each, and it handles everything brilliantly. It also plays .mov files.
Granted, this performance is thanks in part to the powerful processor in the iPad, but the speed boost in working with PDFs is a welcome change to my now-cramped iPhone readers. There are a few UI tweaks that could be made when managing files, it's true. Still, adding folders, moving things around, and so on, are all there like a little mini-Finder. Piling a bunch of data into your iPad is easy and will look good.