Snark aside, I'd say that Siri doesn't seem to work at least 50% of the time.

First, it tends not to be able to connect to the network. Whether with full 3G or even over wifi a large percentage of the time you'll end up with "I'm having trouble connecting to the network" after asking your question. There shouldn't be any excuses here - paid for the phone which the service was a feature, one should be able to use it whenever they need.

Second, the speech to text is severely lacking. Sure it does a fairly good job of sentence translation but anything outside of phonetic names is just garbage. You'll get 'Red Robin' but not 'QDoba'. You'll get the last name of 'Anderson' or 'Jones' but any ethnic name (I'm of German descent - no match, I can't imagine being Indian, Korean, Hispanic, etc.) isn't going to match unless you say it phonetically.

Third, it just tends to be a glorified search widget. Other than reminders or asking about the weather you'll most likely just be prompted to search for what you are asking. And at that point you are back to the phonetic requirements to get what you are searching for.

I'm not saying Siri is bad, it has it's place, but this isn't the revolution it's hyped up to be.