I had to really hunt on the Rogers site to find anything, but I eventually did find the right page. It sounds decent but I do note that emails are limited to 20 words. The rest of the limitations sound reasonable though.

I would guess that like other voice-command type apps, that it's done via servers (otherwise, why would be be charged a monthly fee?), and if we had unlimited data plans, I'd consider it but for now, I will pass. In my case, I don't drive, so it'd have less value for me personally, but I can see the benefit for having such an application for while driving and such.