Gentlemen (and ladies)
I have an HTC Cruise (windows mobile) with TomTom Europe Maps saved on a 4GB micro SD card and a BB 8310 using Blackberry maps. Hands down the HTC won. Why, because the maps were native on the phone and i did not have to wait for them to download. It was fast, precise and detailed. The solution to have them downloaded. Even if the excuse was that you would get 'updated' maps is rubbish. It can easily be done over the air with maps on the phone or when you are syncing your phone.
that's my 2 cents