Google Earth is a program that creates a virtual globe that represents the Earth from the juxtaposition of satellite photographs. It comes in three versions: the free one for common or personal users, Google Earth (Enterprise) and Google Earth Pro that costs $400/year. Unlike older versions, this is available in many languages.
In the beginning, you are offered tips or suggestions that are very helpful to learn the new features that the new version has (usually points differences from version 4.3 onwards). Among its features, you find a “Flight simulator” (I crashed and burned with a F-16 Fighting Falcon, a SR-22 was also available), the Sky and Mars mode (it’s a tool for viewing stars and astronomical images, and high resolution maps from Mars), Street Views and 3D Buildings (not present everywhere, users have their viewpoint from street-level), Google Ocean (new since version 5.0 - users can dive in the ocean).
A definitely surprising feature for those who are new to Google Earth is the possibility of navigating through space and Mars. You can watch constellations, mars, some galaxies get information about our solar system and some other astronomical information (all very educational). I was impressed by the images of Mars’ geography; I spent quite some time navigating through mars and watching the real black and white photographs taken from spacecrafts.
Back to the Earth, the very first thing I did was type in the search box the name of my home town and later, the address of the house where I lived during my childhood. Watching my old neighborhood and my old primary school again after a while was a very nice thing!
My conclusion is that I was able to zoom in or out, navigate and control it without much effort. I just needed to read the manual a bit and start using the program. Its usability is excellent. Besides the geographical information, it allows to measure, draw, save, and print images and positions, as well as import GPS information. But I think the most important is its educational value.