Others say...

"Offline map sharing functionality, great source for geotiff raster maps"
I have been using Topo! since it was a Wildflower product back in the early 1990's. The interface does take some getting used to as mentioned before, but like all powerful software programs (vi/emacs) eventually, it becomes second nature.

I mostly use TOPO! to annotate my previous trips, plan future trips, share travel guides with family, and create georeferenced raster maps for handheld GPS devices.

My trips primarily used to be hiking and backpacking trips, which I would dutifully record using an old Garmin Etrex GPS receiver. The tracks and waypoints would be uploaded to the desktop and saved as separate .tpo files. Back in the day, I was plenty happy just to see waypoint times and elevation gains as documentation of my backcountry trips. I would also use TOPO to create waypoint routes (up to 30) to be uploaded to the GPS receiver so that I could plan/program my future hikes into the Etrex.

Since those early primitive days, both TOPO! and I have changed a lot! TOPO! has improved significantly in its featurea. Now that I have two kids and more money, my outdoor travels consist mostly of Jeeping, dry car camping, and ancient rock art hunting.

Now, with the newer versions of TOPO, it is possible to add pictures and notes. In turn, these more detailed maps can be useful as travelogues not only for nostalgia, but also as travel guides for family members and friends who are using TOPO! as well.

While similar functionality could be obtained by using Google Earth or Maps, this map sharing is dependent on "cloud computing". This may be feasible when sitting in a coffee shop in a metropolis or even at home, but out in the desert without cellphone access this is not a viable option. Further, Google Map data is only protected by obscurity. Any person who knows the URL to your map data can view it.

Since I don't have to carry gear on my back anymore, I primarily use TOPO in the field on a laptop with an external GPS receiver. Though bulky, it is a much more useful combination than simply a tiny handheld receiver alone due to the larger size of the laptop screen and the ability to search for waypoints using the standard keyboard. My family uses a similar setup and they too find it reassuring to know that they have a clearly mapped GPS route available to them in the wild.

Finally, the most useful aspect of TOPO! is unfortunately no longer available, unless you can beg, borrow, or steal a boxed Xport Pro package. NatGeoMaps recently and quite quietly killed off its entire TopoPro line (including for ArcGIS). Xport Pro (formerly $199) allows the user to export high quality USGS maps in the georeferenced GeoTiff format. These GeoTiffs could then be used in shareware GPS programs like OziExplorer for Windows computers or OziWince or NoniGPSplot for WinCE GPS devices (many personal navigation devices can be cracked to run these apps in addition to the installed street mapping software). It used to be that you could call in a credit card number to NatGeoMaps customer service and for $99 get the functionality activated through a PIN, but no longer :( .

Admittedly, GeoTiff, mrsid, and many other georeferenced maps can be downloaded from state governments (usually from depts of ag or wildlife management), but having it all in one software package on CD's is pretty sweet.

"Good Accurate Mapping "
All information is in USGS 1:100,000 scale for road and very good hiking mapping and navigation. Its all very, very easy to learn and includes cool features to customize your maps like adding notes, showing your trails and routes, elevation profiles for hiking mountains and a 3D feature. This allows you to actually view your route as your travel in simulation at varying angles. The `Search' feature is very handy in locating just about anything you are looking for in that section/region of the map. You can zoom into five different levels of detail and print out any portion of that map. If your GPS allows you to import information, you can upload your personalized map to it. You can also import most GPS information into your computer onto the topographic maps, such as .gpx files and geocache information. TOPO! National Geographic is the best in mapping information for GPS or everyday route or hiking planning.

I had a Magellan Triton that claims you could download the maps to your Triton handheld, but that software is flawed and I had to return the Triton four times. Now that I have a Garmin, I can download info to my PC and use the National Geographic TOPO! information, but I still cannot import maps into my Garmin (just geocache information).

"National Geographic TOPO Maps"
This product is very hard to use, especially if you are trying to download it to a Magellan Triton 500. Not user friendly or intuitive at all.

"Buyer Beware!"
I bought this software based on the belief it would show trail maps for hiking. Trail maps are only available via a download (not a big deal), but trail maps for PA and NJ don't exist!!!

If you want maps that show existing trail maps for hiking in PA, do not purchase this software.

"0 stars. Ripoff. Can't download maps to GPS"
After spending $250 on a GPS, $40 on a memory card, and $100 on this software (all at the advice of REI (yeah, I bought it from REI, not Amazon)), I saw that the fine print of the software says you can't download the maps to your GPS.

What's the point of having maps sitting on your computer hard drive that you can't download to your GPS? My computer hard drive isn't going hiking. My computer hard drive isn't hunting for difficult-to-find street. My computer hard drive isn't doing a search and rescue mission. Oh, but if your computer hard drive ever DOES want to go hiking, it won't get lost. You, on the other hand, will be lost and out $80-$100 if you buy this software.

If you thought National Geographic was a reputable organization, they're not! (And I guess the same is true of REI.) And does Amazon warn you about this -- not that I've found so far.