I've been using Siri for years. Texting is occasionally hit or miss (although simple things like "On my way" or "Be there in 15" are reliable), but there are a ton of things that are way quicker than typing (and completely reliable). "Directions home", "Movies playing near me","Open app X","What was the last Tigers score","Call Amy",most Google searches...

Maybe it's my flat midwestern accent, but I find that Siri gets it right almost all the time with these things, and I find it way more natural and fast than hunting for an app icon, especially while driving/walking/biking.

Texts and emails are not 100% accurate of course, especially given my accent and given that proper nouns can be problematic. But it's still faster for me to start these activities by voice and just fill in the corrections. Searching for trivia (to settle random arguments etc.) is always, always faster with the OK Google interface.

For almost any activity on the phone, hunting for an app icon and finding the appropriate context in the app (e.g. searching for the correct contact to send the message to) etc. are usually the most time consuming and frustrating activities. Those are nicely bypassed (with a very high level of accuracy) by the no-touch interface of the MotoX.

Creating calendar entries and setting alarms etc. are two other activities where natural language queries are pretty much the best UX compared to any screen based UI on any device. Google Now has extremely high accuracy in recognizing these tasks.

I use voice to set alarms ("set an alarm for 5:30") and to open up Pandora when I'm driving. Both work great. Texting is a little more hit-or-miss but it's normally pretty accurate. I try not to text and drive anyway, even if it's done by voice.