I was just checking out my XP tonight and it is still going strong after several years. I had to read the manual again but thought I could share my experience - even though late to the thread.
The display in the window is fleeting to say the least; however, the meter remembers the value and it will be there to recall if you push the memory button on the left side of the meter.
Perhaps this is why its batteries last so very long - quite energy efficient really.
I think I'll take it out with my new D800 and see how much they agree. Of course, this is APUG so I had also better bring along the Contax, Shen-Hao, or Bronica. The 8x10 can stay home! ;)
On my XP when I'm pressing the "measuring" button, it blinks 2-3 times with the value. However when I press the "memory" button and keep it pressed the value doesn't blink. That's how I usually use the meter.