It's very frustrating and makes me not want to use the function. In a car or moving around I often experience network blackouts in the Countryside or underground on the tube. Why doesn't Apple introduce off-line functionality for simple Siri tasks such as calculations, calendar entries, reminders and searches of data contained in the phone? For me the most frustrating thing about Siri is asking a question and watching it spend half a minute working out a solution.
Agreed. Even the iPhone 3GS had simple offline voice commands. Not everything needs to be bounced off a server. Apple will eventually implement it, as it's a common criticism. It's just a question of when, really.