I think the Nokia E90 is a very powerful device that has been refined from the older series 80 line of communicators. This phone has almost everything: Symbian S60, 3.2MP camera w/AF, wifi, high resolution screen, comfortable qwerty keyboard, 330mhz processor, microSD slot, etc etc.
In case you are asking yourself what is so significant about Symbian S60, let me just say that it is an operating system that is infinitely expandable, and very easy to use. Unlike winows mobile based phones, S60 knows that it is suppoed to act as a phone first, and a computer second.
And yes, to answer your other question, it has built in GPS...full GPS...not just something simple like google maps.
I found a review for you that I remember reading a while ago:
www.mobile-review.com