The curvy roads option is something I never use and really do not see a need for it. The GPS when not following a pre made route is just so I know where I am and what is coming up. Also useful in determining how much time is needed to get to a certain point or even home if you need a plan in a hurry. The main use is making routes beforehand to follow that day. The unit is set on shortest route and I use Base Camp and Google Maps to build the route I want, not one the unit chooses for me. The shaping points I use insures me I'm traveling the roads I found on google earth etc. that I like and the counter helps in timing my arrival where and when I wish, like for lunch at lunch time. If running ahead or behind schedule the pace can be adjusted along the way. Anything from memory, given directions, a paper map, cell phone without help or with a program, cheap GPS to expensive GPS will prob get you where you would like to go but a huge difference how well each one will work. The top of the line units like the 595 while expensive are fantastic and can not be equally compared to a cell phone any more than the phone can be compared to a paper map. Each is better than the other. Almost nothing is completely water proof as even a submarine will implode if it goes deep enough but the Zumos can get totally wet without a problem. The vibration resistance, left hand controls, glove friendly screen along with no rain worries makes the 390/395 and 590/595 the top choices for motorcycle GPS. The built in music, blue tooth ability and the tire monitors are just nice extras. The other Zumos are also great but as said no longer made and some no longer supported by Garmin.