We are in Texas and have a black pebble finish pool that we like a lot. Our builder said the temperature effect is minimal, but without a control in the experiment, it's really hard to know. Our pool gets full sun for 4-5 hours per day, we have some live oaks that provide some shade. Last year it got a little warm (above 90) but my friends with light bottom pools had the same problem, one had a very light grey finish, no shade, and his was much warmer than ours. So I think the amount of sun is the bigger factor than the color, as are depth and size, ours is 25k gallons, I've heard smaller than that, you will have problems with getting too warm. Seeing the bottom is not a problem, at least it hasn't been a factor for us, and we have several ledges and a beach-entry.
Some pics:
I wouldn't hesitate to do another dark bottom pool, but as always, YMMV.
-John