The book that has "unofficially" been released as few days ago is now officially released. Besides being in hardback, it is available on iTunes for the same price as retail. I purchased the iBooks version for two reasons, one is I hate carrying books around. I also find the iBooks just as easy to find stuff as the paper and it gets updated with FAQs and you can touch a rule to get the description or jump to the stat page.
PDFs are nice but I actually find the scan versions horrible for me to read. The other issue is a few local tournaments require a legit copy. I think this is good because you have to assure that the document is tampered with and you are at an establishment that sells the books. Tampering isn't that easy to do effectively but it happens.
I have to say I will do a more formal write up in a few days but I can say I really like the codex. There are a few nice builds and I plan to make a couple fun lists for the fluff of it and a tournament list. I have also read some different interpretations of some of the rules. The big one is Typhus and Zombies. Typhus clearly says you can't purchase options with his zombies. Some groups say that means wargear even though additional cultists are listed under options. While I love the idea of flooding the board with more zombies than you can shake a stick at, most groups are saying RAW. I hope it gets FAQ'd. Friendly games are fine but you should check with your TO before putting time and effort into making 210 zombies to find out you can only field 60.
There are lots of neat options available for most of the army. There are a few nice buys and a few meh. The one thing I hate is 1k Sons still being Slow and Purposeful. This is pretty bad for the points. Chaos Lords rock with their options and bikes are a good price. I think that the army will provide enough variety that people will be able to get the most out of this dex for a long time.