And like Sensorly you can see the updates online http://www.rootmetrics.com/
A couple of tips for those using it based on my observations of the app:
To get data speed numbers, first Switch the Coverage Report to Data Speed.
Tap and hold on a hexagonal color to drop a pin. You can then look to see how many samples were taken.
Tap on the icon that comes up that looks like a graph to get average up/down speeds. You can also compare that location with other carriers.
When looking at Coverage Reports, the RootScore is a combo of the Signal Strength and Data Speed reports. I like to look at all three reports on a location.
The app cannot be run in the background unlike other GPS apps. If you exit the screen while collecting data, it pauses collection until you return and then tap the Play button.
The hexagons aren't very big, so if you are driving and collecting, you may see gaps between hexagons if you're a speedy Texas driver like myself. You just have to collect data a few more times to get it all.
Also since the hexagons are small, you may have to zoom in a bit to see them.