Siri has always been pretty useful for the things I use it for: setting timers and reminders, and turning off my lights after I'm in bed.

Agree 100% ... but it would be nice to have some softer edges around those things, where I don't have to be so prescriptive and robotic in the way I make such requests. For example if I set a 15 minute timer, I'd like to be able to follow up five minutes later with "actually that 15 minute timer should have been 16 minutes" and not second guess whether it will do the correct thing.