As a red/green colorblind person, I really don't have a problem on the phone - but then my condition is moderate. There is a lot variability in degree. I do actually see red and green, its more differentiation among very light or very dark shades of brown and green as well as purple and blues. The overall tones in the environment can affect perception as well.
My biggest problem with color perception tends to be traffic lights at night. The green light appears more dirty white at night and will get lost in other lights.
I'm pretty much like everyone else, I would prefer more color selection within the themes. I can certainly see 21 different shades of tiles in the color selector, but looking at several of them individually, I couldn't tell you some of their "correct" colors