Christian Reber:

Every day, we work with the goal of making Wunderlist even better. We want to constantly improve the way we help you get stuff done. So much so, that this year you will see Wunderlist help you get stuff done in smarter, more intuitive ways. From an intelligent way to capture to-dos and sort lists, to productivity-boosting integrations with your favorite apps—2015 is going to be big!
[…]
Arriving soon, Folders will make it incredibly simple to keep your personal, family and home lists separate from all of your work and project lists—yet they are only a tap away when you need them.

I’m very excited about all the announced features. Especially folders will totally change the way how I use Wunderlist. Love it.