Mobile E-Commerce Forecast for 2013 by eMarketer. On the top level, is averages to $130 gross spending per user for 2013. Interestingly, tablet usage for 2012 is more evenly distributed across age groups, particularly for the children and elderly. This general adoption for tablet seems to suggest that tablets have more diverse type of use case for different needs across the population (i.e. children - education and gaming, elderly - reading, emails).
Furthermore, it is curious to note that Gen Z has lower mobile usage on average than Gen Y. I wonder if this is not accurately accounting for Gen Z’s currently weaker purchasing power. When they move up to the next age bracket, their adoption rate could likely be higher.