I totally agree with a lot of others here. The background image in the ingame UI needs to be gone. Also the rest of the UI elements should get some transparency or adjustable colors.
Not only does the background make you blind with the UI open. It also feels like it disconnects you from the game since it looks so jarringly different from the game environment. Quite an immersion killer and rather impractical – especially since it lacks so much of the functionality of the old UI.
The UI does look ok as a main menu (though I still kinda prefer the old one) but ingame it really doesn't work for me.
(in fact it ended up bothering me enough that I decided to stop playing for now until it receives some improvements)
As far as the main menu goes. The old menu started you off by looking at a guy standing ona lil island surrounded by water... a perfect introduction for what awaits you when you play. The new UI looks more like a mobile app. Certainly nice but also boring, emotionless and a bit disconnected from the actual game.
That beeing said I think that both ingame and main menu should be somewhat transparent and show actual ingame scenery in the background.