SMS is more popular in Europe than it is in the US. Generation also effects on the use of sms and instant messaging for example young people in the US are much more likely to use SMS while its very rare to use of sms in Americas. Sms is more popular in Asian Countries where people use less instant messaging system as India, Pakistan etc.
Main problem of sms is its limitation and its typing. It takes too much time to type and has a limit of words.