No it won't be able to switch between calls and data. It can multitask - same as any other iPhone, but not access internet (unless on WiFi) and be on a phone call.
Please remember that this is not the case for ALL carriers. I believe only Verizon has this limitation.
All other carriers have the ability to use the internet AND talk on the phone at the same time.
For example, I am on the Rogers network in Canada. Moments ago I was surfing the internet at the same time I was on a phone call.