A few more quick thoughts:
1) The voice commands do seem a bit of unnecessary 'fluff' . . . except! . . . I can't tell you how many times when I've been on a fairly long trip (1 hour or more) with someone else in the car, and have gotten so completely emersed in conversation with others that I miss a turn off. I've also done this sometimes when just talking on the phone (headset of course). So, it's kind of nice to have a pleasant voice recapture your consciousness to remind you that you'r approaching your jump-off point. (voice is female or male selectable & volume can be adjusted . . . my wife & I both prefer the female) Some of us have more tendencies toward that kind of "absent minded" attention to trip navigation, but it's something to consider.
2) A very helpful benefit that I forgot to mention, but which I personally enjoyed this past summer while exploring unmarked, unfamiliar dirt trails up in the heavily forested Sierra Nevada. There is a "bread crumb" feature that marks otherwise "unknown" paths as you travel them. In other words, if there is no record of a road in the Navi's data bank, it will "create as you go" with a dotted line "unknown road" marking that stays on your system until you clear it. Its a great reference with which to check your progress & relative position to where you've already been . . . or even with which to return the same way you came, if you really get perplexed & decide you don't want to explore any more new places. Or you can retrace your tracks & revisit later (another day?) if you find a great "secret" location you want to share with others or just enjoy again.
3) Just FYI, the only real established roads I have not found to be loaded in the Navi data base are those on military installations. But that is true of other mapping services as well (such as mapquest). You just need to get a map from the base (or in some cases they are available on-line via official base sites). I'm guessing this is some kind of a government red-tape (data access difficulties for companies compiling street map data) or a security issue (although you wouldn't think they'd have maps on their web-sites either if security was an issue?). So, just be advised you'll have to look elsewhere for on-base maps (this is based solely on my experience with Camp Pendleton (Marine base) in SoCal).
