I recommend both. GPS devices fail, get lost or stolen, ask me how I know. Maps also contain a wealth of information that GPS haven't been programmed to supply, at least not yet.

In any case, plan your route before you set out in the morning. Most times you will be staying at a hostel or some other lodging and the staff can sometimes assist with route planning. I ran into a lot of people that can't read a map, so don't count on it. The point is, spend time working out which road leads out of town. I am recommending this because I usually don't and sometimes I pay for my lack of daily planning.

In medium to large cities it can be very difficult to figure out how to "escape." Here is where a GPS is usually very helpful, but not always. Trying to leave Cusco, Peru, the little demon kept sending up ridiculous routes, that turned into impassable farm roads... On my final exit from La Paz, Bolivia, there was a farm worker strike and the main highway was closed. The GPS took me up every goat path imaginable, one that turned into stairs! Putting in time the night before won't have saved me from road blocks encountered after I set off. The GPS did get me to the highway eventually. In the end I rode the bike slowly with the river of people walk around the protestors (all car traffic was turned back...) I didn't ask permission and no one stopped me.

__________________
Peter B
2008/09 - NJ to Costa Rica and back to NJ
2012/13 - NJ to Northern Argentina, Jamaica, Cuba and back to NJ
2023 - Peru, Brazil, Paraguay, Argentina, Chile, Bolivia...back to Peru.

Blogs: Peter's Ride

Peter, interesting.
I've seen the same thing happen to people using GPS here in Mexico, lately, too.

I notice that the recommendation advocating maps, have been coming from riders with lots of in country experience and strong Spanish language skills. For those that don't speak the language, chance are a GPS will get you where you want to go and gives the best advice when you are at an unmarked intersection miles from anywhere or anyone. They aren't perfect, but the maps are getting better all the time. If you can afford the commercial GPS maps, get them. There are free GPS maps (open source) that are in some cases better than the commercial maps. garmin.openstreetmap.nl (based on the Open Street Map project.) The OSM maps are improving because thousands of people extend and correct the maps every day. Any decent GPS will support loading more than one map set at a time. So can load Garmin Mexico and OSM map set covering Mexico and beyond on your device and switch back and forth as needed. I recommend only selecting one map set at a time.

Regard buying maps in advance verses when you arrive. The maps you buy on the road are in Spanish, and in Brazil they will be in Portuguese. There is lots of info that you can figure out, but some you might not. I couldn't find maps of Guyana when I entered the country in the south at Lethem. I might have been able to find one in Gergetown, but by then I was leaving the country. Finding the right kind of store, one that sells maps, can be a cultural experience. In Bolivia I found maps in a magazine store. I never could find maps in Jamaica, free or for purchase. Some tourist offices have maps, when you can find the office and they have them in stock. I made the rounds to tourist offices in a few countries and now have a good stack of maps. You'll also get lots of other good tips in tourist offices. Sooner or later, you'll want a low level of detail, bare left here or go straight then turn later...and your paper maps won't have it.

I used a GPS in San Salvidor (El Salvidor) and Crete (Greece) to get back to our hotel at the end of the day without having the local map data properly loaded. I had set the hotel as a "favorite" then drove around in a spiraling fashion (without street detail mind you) until we were back on the right block.

Some say over plan and be ready to improvise. Helmuth von Moltke the Elder said, "No battle plan survives contact with the enemy." I think that applied to travel and route planning too. Adventure is full of the unexpected. Preparing is full of personal choices and trade offs, so pack to your comfortable level. In the end, if you want to make God laugh, tell him your plans.

__________________
Peter B
2008/09 - NJ to Costa Rica and back to NJ
2012/13 - NJ to Northern Argentina, Jamaica, Cuba and back to NJ
2023 - Peru, Brazil, Paraguay, Argentina, Chile, Bolivia...back to Peru.

Blogs: Peter's Ride

My language skills are marginal at their very best (Spanish, Portuguese, Dutch, Hindi, Guarani, you name it). I liked my paper maps, and for the most part I liked searching them out, buying them, studying them, folding and unfolding them, marking them up, and sharing them with local people who had often never seen their landscapes rendered on paper.

When I traveled with riders who used GPS, we sometimes found them useful but just as often were led around in pointless circles in absurd heat or drenching downpours which we only resolved when I insisted on stopping to ask for directions--generally using combinations of gestures, sign language, absurdly inept local language skills, drawing pictures, role playing, etc. I have no doubt that in the right hands and under the right circumstances GPS is a tremendous support. In the wrong hands or under the wrong circumstances it's been (for me) a real distraction from everything I enjoy about travel.

Naturally, YMMV.

Mark

+1
I've seen people want to fold a GPS that has them frustrated and riding the wrong routes.