I just downloaded Google Earth, and I have been using it for a little while this morning. It has been an absolute blast playing with it. If you're into maps, geography, or just playing with very cool applications, this is worth the download.
The bigger and more popular areas have more detailed pictures available. Although, if you live on rural farmland somewhere out in the middle of nowhere, then the high level detailed pictures of that area could be limited.
To download it, go to the following site. Note: this application does require a high speed Internet connection, fast computer, and a good video card.