Hi Mike - I have Anywhere Map runing on a Ipaq 5550 using a bluetooth gps receiver. I don't have the pocket plates feature, but here's my opinion based solely on my experience.
Pros - Anywhere Map is good stuff. Plently of features to keep a nerd like me occupied - and it gets you where you want to go. The price is not bad.
Cons - After numerous system crashes, freezes, and lockups, I do not trust the pda anymore for navigation. These also occur when using Copilot Live (ironically named software for car navigation) or other generic software, so I feel the problem is not with the Anywhere Map software, but in the pda operating system, bluetooth interface, or one a dozens of other hardware/software possibilities.
Also, the pda screen is difficult to see in sunlight; with some sunglasses, it's almost impossible to see anything on it.
In the car it's very frustrating to try to reset, relaunch, and reload your navigation. Flying VFR, I would keep a sectional and airport data handy. For me, there's no way I'd use the pda as a necessary component of IFR flight.