- Sharing you location is a very basic need in communication (don't think Google Latitude on smart phones, think 90.7% of mobile phone calls including the question "where are you?", globally, everywhere)
- Landmarks is a concept that has evolved to solve this; Well known places that can be used to communicate location. And they fit the text based communication perfectly.
- Traditional maps, which can be seen as a competitor, lacks in a few major areas:
→ How do you send a map? SMS is the global standard of communication, you can't SMS a map
→ More than half of the people in the world can't read maps. At all. These people still understand the local landmarks.
→ Good maps are not available everywhere, and will not be anytime soon as traditional maps are expensive to make
So revolutionary in quite a different way than BBM or iMessages.
(edit: formatting)