I don't have the Ultra but I bought the series 7 about 3 weeks ago coming from a series 4 and have noticed the same low brightness when in a dark environment.
I updated to 9.0.2 yesterday and it seemed like the screen was brighter in the dark, not as bright as the 4 but bright enough that I could read it without straining.
I updated to 9.0.2 yesterday and it seemed like the screen was brighter in the dark, not as bright as the 4 but bright enough that I could read it without straining.