I have been comparing the 3597 to my 1490LMT. Limited test but the GPS as a stand along GPS is much improved. The unit design is Apple all the way but clearly the Nuvi firmware group don't talk to any other group. Touch screen is much more responsive. Split screen for junction views is great. Voice directions are improved. Searching google on your iPhone and blue toothing the info is really helpful. 3D dem maps are included for use with CN maps. Lots of really cool stuff on the unit.
When it comes to BaseCamp it seems clear to me the Nuvi firmware group does not intend to support BaseCamp. Example: Legacy file system.
Both my Dakotas allow me to delete geo data (waypoints, tracks, and routes) from BC. To delete geo data on the 3597, I have to go to Trips and delete routes, go to save data to delete waypoints, go to settings, device, and clear travel history. I have not upload a track from base camp to see where it would show up. In addition I have to mount the GPS volume on the desktop go to the GPX folder and delete all files I fine there plus empty the trash.
I am sure the nuvi firmware group is saying Nuvi users don't use BC. Any why should the spend hours creating a customized route if they can't load it to the GPS without getting a different route. I can and will continue to use BC with my Nuvi, I can make it work pretty well, but when the casual user starts seeing routes in BC on the device they can't see on the device, they probable blame BC.
The verdict is still our on Recalculation of routes but it is not look good. I just uploaded 9 routes and BC noted the routes were calculated from CN 2013.4 but the 3597 has 2014.1 and BC ask if I wanted to recalculate. I said no and it takes forever but I have 9 Routes in Trips and they match the uploaded routes perfectly. All routes I have tested start for my home and I am at a different location now. Different from the 1490, the 3597 does not ask me where to start from, it starts from my current location. When I hit go the route gets recalculated and I want to be home to be totally sure but I think the route will change depending on the 3597 route settings. I will keep trying but it done look like the nuvi group is talking to the zoom/Montana group.