new version, google earth 4.0 beta

i've downloaded two versions for windows, one is ordinary, the other is professional. but the ordinary one can't be launched sucessfully, i can't experience it.
after i installed the professional one, launched, it requires me to input the licence key(free trail or purchase). i don't want to pay any for this software(just want to experience it), so i try to register a licence key for free trail.
finally, i get the key, and log in. but unfortunately, i can't contact to the server. maybe it's the firewall? no, i've checked it to be an exception.
so, i can't experience it. what a pity. reading the article "what is new", it just talking about the news about the toolbar, and didn't refer to the quality of the graphics. after all, it has a new interface and gives out a nice look and feel to the users.
why purchase? it's worth? i'm not sure.