I have the Montana 650t with the topo maps. Compared to my old one, it works much better, boots faster, and has a large battery for good life - plus it can use AA batteries as well as its own rechargeable LI-ion.
They have a lot of features. You will have to do some research to download data to your computer, it's not obvious how to do it, in Garmin's instructions.
I always have a backup to the GPS, though - maps, etc.
