I'm not at WWDC 2015. Unfortunately!
But this year Apple has made it a much better experience to follow along without a ticket. They release WWDC 2015 videos on a daily basis and even stream some of them live.
I watched the keynote which gives a good high level overview of what is coming in iOS 9.
But the annual Platform State of the Union is something that I appreciate a lot more. It is way more developer focused, as they dive into code to demonstrate new features and APIs, and you get a good idea of where to focus next (related to your own apps, or new projects).
This year it seems Apple Pay and
PassbookWallet is getting a lot of publicity since they want to increase adoption of Apple Pay and show that it's getting better and better. In Wallet - The home for Apple Pay and more you get a very good overview of improvements to Apple Pay and the future role of Wallet, that is replacing Passbook.
In Apple Pay Within Apps you get a hands-on demo of how to integrate Apple Pay into your own apps and some guidelines and best practices on design, what users expect and where you should focus.