You can use it as a normal phone as well (as long as its always on) and Android can be installed on it as well.

Main reason is I am finding so much evolution in iphone apps e.g pdf readers with annotation, voice dictation etc etc and I can just shake my iphone 4 and it logs into my home computer via RDP for everything else. Also I have a UMID umpc (with keyboard) and my iphone 4 has its own insurance for loss and theft!. The Viliv s5 is a great device though!