Its a rip-off of HTCs version, or Google's (which is also a ripoff of HTCs). It is rubbish, but if you tap the screen it loads the videos and images underneath and you can tap them to remove ones you don't want. Tapping the note in the top right lets you change the music. At the moment, you cannot add images or videos, cannot edit the title and it only had about 5 different tracks and you cannot add any more.
Hopefully these things will come with updates quickly, because you cannot create movies through Googles Movie Creator on the Z2 for some reason, which is really annoying as I really liked using them. Sure there are the new Google storybooks, but they are image only and no sound. I am frequently amazed at these oversights by huge companies. HTC got it pretty much bang on.
Sony - you get so close to making a really awesome phone, but there is no attention to detail like Apple or HTC. Very annoying.