I recently got a Surface Pro, and have been using it for the D&D Next PDFs along with a couple other games, so can relate my experiences.
PDFs are difficult to share at the table. We usually share the books around the table, someone looking at the Monster Manual while another is looking at the Player's Handbook. It's probably not a good idea for the PDFs to be your only source for the material, as it will increase your waiting time to get access to a book. (Also, some of the players are not as careful as I would prefer to be passing around expensive hardware.) I would recommend PDFs only if you are the primary user with little sharing.
Switching between PDFs isn't trivial. This will depend on the software you use, but even with my PDF reader keeping the page I had open, I can still get lost switching between books.
You may need to start remembering page numbers with PDFs. With books, I would remember about where in the book my content was, open to a page in that area and go backward or forward from there. That's much more difficult to do with PDFs, and I ended up just memorizing a few of the more frequently traveled page numbers.
Load times on PDFs can slow you down. I have a few PDFs that can take a while to load each page due to the resolution, making scrolling through them quickly frustrating. This is based a bit on hardware and a lot on the PDFs you are using, though.
You can't "save your spot" easily. I will often be looking at one page, and discover I need to look up a table elsewhere in the PDF. I can't just put my finger there while scanning through for the content, instead I need to remember the page number.
That being said, there are a few up-sides:
- Ctrl-F - easily the best part of a PDF. Being able to find some random text in 350 pages is amazing.
- ToC and Index links - If your PDF is set up with them, they help a lot with navigating the book.
- Scrolling feels nice - This is strange but true (for me). I enjoy scrolling through the book with a tablet compared to a book.