I agree that the range indicator isn't all that useful. I'm almost always running the battery to empty whenever I do my 77 mile commute, so range is a very important thing for me to be aware of. The SOC (battery level) indicator is the most important tool, and it's accurate in that when it gets to 0, you're done.
The way I use the dashboard is to reset the trip meter when I start (at 100%) and check my range every time I get to factor of 10% SOC. (90, 80, 70, etc.) Then I calculate my expected range based on the past range. E.g. Say that at 90% I've gone 10 miles. That means if I keep riding in the same way I can do 100 miles. Over time, that maximum range will change as I go faster or slower, but given that I have a specific range I'm trying to get to (77 miles), I can use that simple calculation to tell me if I can go faster (i.e. use more energy), or if I have to slow down.
The range indicator does settle down if you can hold a constant speed for some time, and that is the number you should use for your range estimate. Changing speed (accelerating or braking), changing elevation (going up or down a hill), and wind (head or tail wind, or drafting behind a bus) will significantly affect that number, so you have to decide if you are going to be in that state for a long time, or if you should ignore the indicated range for a while.
I like the way that my van estimates range. Basically, it uses fuel remaining with an average fuel consumption per mile. I'm not sure how long it keeps data to make the average, but it's fairly long, so if I've been driving conservatively for a few days and then I drive like a hooligan, the range estimate will be very wrong. I can manually reset the counter when I change my driving style to get a more current estimate.
Once nice thing about the fast changing range indicator is that you can immediately see how what you are doing will affect your range. E.g. See how the range is affected when you sit up vs. hunch down, or when you go faster vs. go slower.
