First, it would be nice if it worked more often. About 30% of the time I get the "unable to connect to my server" message.
For Siri to make an impact, it has to be available. Otherwise, I don't think people are going to keep trying to use it.
Second, more databases, sure, but I'd also like it to do more with my phone. Especially toggling settings that are tucked away.
Would love to be able to say, "Turn on my personal hotspot." Or, "Disable Bluetooth."