If you've been following our Devstreams - or Steve's twitter - our plans to release a visual update to our UI shouldn't be new. But if you haven't followed - the short explanation is that we're redoing our UI art style!   Different themes (see some examples above), a more evocative and artistic UI, it's all coming - but not all at once! 
Right now we have exactly 131 screens in the game that need an artistic pass to the new style. 8 we have done and ready to go - they'll be launching soon. Themes similar to above are coming for the the screens we have completed, and all subsequent screens will inherit whatever UI theme you've chosen (default or other purchased themes).  So, 'all subsequent screens'. This will be rolled out over the rest of the year - we are not launching all 131 screens with new art at once.Things like horizontal scrolling are being removed based on player feedback, and we're going to be addressing other common requests as we make our way through the redesign. The busiest screens are particularly hard to change, but we will slowly but surely make our way through. 

Thanks, Tenno! We'll open threads once this is released for practical feedback, for now, this is just some insight into the coming change!