Nav Systems
I got my first in-dash Nav system when I bought a 2001 Acura 3.2 CL Type S in May'00. I've used it to travel up and down the East Coast from NH to GA. When I went shopping for an SUV to replace my sporty coupe, I began with the requirement that it come equipped with a Nav system.
Having used the Acura ('00 vintage) system for years and the Toyota ('03 vintage) for three weeks, there are some obvious differences.
The Toyota system is lightning fast compared to the old Acura. While noticeable when establishing a route, it really shines when recalculating on the fly. The Acura would often need so much time to figure out a new route, you would be past the desired "next turn" before it told you to turn ... so it would have to recalculate all over again. And again. Etc. The Toyota '03 recalculates the route in about a second.
The Acura system worked all the time. The Toyota system cuts out most functions when the vehicle is in motion. While obviously an attempt to prevent drivers from playing around with the dashboard while driving 80mph on the highway or slaloming through a school zone, it is incredibly annoying. If you want to do anything useful, you literally need to pull over to the side of the road to get directions. The Acura would let you risk life and limb as if you were an adult capable of making your own decisions in life. The lack of "on the move" programming in the Toyota is all the more frustrating when there is a passenger in the car and that person is also estopped from using the Nav system while the vehicle is moving. If there is an option panel somewhere which shuts this "feature" off I haven't found it.
In the Acura, the Nav system doubled as the HVAC control; in the Toyota, it doubles as the stereo. The Acura system was better because you had full stereo control on the dash at all times, while you would leave temperature control to the automatic climate control system. The Toyota method makes dealing with stereo functions rather kludgy feeling ... and it requires you to diddle with the buttons on the touch screen. Why it is safe to diddle with the buttons to change radio stations while driving 80mph is beyond me, but you can do that even though you can't use the navigation functions.
The Acura system let you search for addresses by city and state; the Toyota system uses "regions" which are made up of half a dozen or so states each. This can be confusing if you want to find "400 Broadway" because there are a whole lot of Broadways in a given region.
The Toyota system has great on-screen features; there are many configurable map views providing different means of showing you where you are, where you're going, and how to get there. You can even do a split screen to look at two places (or two magnification levels) simultaneously.
The on-screen ergonomics of the Toyota system are better than the '00 Acura, but the overall ergonomics are not as good. The on-screen "soft" buttons are located a fraction of an inch from various off-screen "hard" buttons on the dashboard. It is very common to hit a "hard" button when you meant to hit the touchscreen. I've sent the screen into Open mode, changed stereo settings, etc. when simply trying to adjust the scale of the map with a soft button.
The Toyota system has a built-in maintenance calendar (you tell it when you need oil, filters, brakes, shocks, etc. serviced and it reminds you on-screen to get it done). I was very surprised that my dealer didn't set it up for my first scheduled service automatically.
The Toyota system also has a "memo" calendar if you want to use your $40k+ car as a PDA.
Overall, the Toyota '03 system is far superior to the Acura '00 system, although there are features of the Acura system that I miss. And in fairness, the '03 Acura system (as tested on an MDX we considered buying) has new features of its own, including a "bread crumb" map (when you are offroad, it generates a track of your travel so you can find your way back to the main road); voice control (so you can operate the system while driving without taking your eyes off the road or hands off the steering wheel); and a rear-view camera system (when the vehicle is in Reverse, the Nav screen is replaced with an image from a digital lens mounted to the rear of the vehicle).
Hope this helps. Stay safe ...