Speed and computing power are the major iPhone 4S upgrade.But Siri is the real innovation and marketing 'sexiness'. And it should be: It's new. It's has big ambitions. It has bigger potential. And its more innovative than we give credit for.

... But what makes it so ambitious, potentially large and innovative: also makes it flawed (at least today). More often than not, my Siri experience looks a lot like the below screenshot. It is slow, unresponsive and often unable to connect to a network (even when on 3G and/or Wifi).

Daring Fireball explains why this happens and speculates why Apple may have intended it:

"Don’t forget that there’s a server/cloud-based backend that is required for Siri to function. I can’t help but suspect there’s some truth to this tweet from Mark Crump, speculating that Apple might be limiting Siri to the 4S simply to restrict the server load while the service is “beta”. There could be 100 million iOS 5 users by the end of this weekend; there will only be 1 or 2 million iPhone 4S users."

There are benefits to being cloud-based. Namely, Siri is still a beta-product and Apple can continuously roll-out updates and make service improvements without releasing iOS updates. And it makes the product more lightweight... but the downside, of course, is that the network can become over saturated and overweight. Network connections stall and users experience delays... or breaks: