pretty dismal
Well now, with the excessively bloated java being the most common language for apps, and windows being the second most common platform, the security holes in smartphones are abundant, and there is little to stop hem becoming the botnet drones most people let their desktop / laptop become.
the scary part is that if Jobs was right in the desktop and laptop market dying off, these limited resource devices will be the ONLY area for malware to infect. so the "hardware is cheap" development model that creates the gaping holes in security will gurantee that the smartphone is even more infested than any pc.