I've had my Digiflash for about 6 months. The first battery is still going, although a few days ago I got the "BAT" signal on the display when I took it out of the camera bag. That cleared after I took a reading, but I take it as an indication that the battery might be nearly exhausted. I have a spare battery in the camera bag just in case.
The only thing the battery does when you're not pressing buttons is hold the memory and display active. You know how long and LCD watch battery can last, so I don't think the constant display is a huge drain. The constant display is one of the features I like.
I love mine. When shooting one subject, I mostly take an incident reading, then shoot until the light changes. Then I note the last EV on the display, take a new reading, and adjust the correct number of stops to the new EV. I find that a fast and efficient way to work without a lot of dial twisting. I love the size and speed, and having an incident meter that's easier to use than a small gray card.
The readings on mine stay right with my Luna Pro F. My guess is that they've linearized the response with a programmed PIC rather than circuitry. I wrote an review in the articles/equipment reviews section that mentions some anomalies I noticed under flourescent lights.
Lee