The iPhone way more than the Mac.
I think the “problem” with the iPad is that, for the majority of people, the iPhone and other smartphone devices do the job they need enough. A lot of people do all of their everyday computing on their phone, and see a tablet as a device they don’t need.
For professionals, there are already iPad-based solutions for a lot of tasks. I know designers, artists and musicians using the iPad as their main device. There are tools like Workflow and Readdle’s productivity suite which add power features to iPad. And Federico Viticci knows all the other tricks to make the iPad a powerhouse.
For the highest of computational demands — like 3D rendering, virtualisation, etc — the iPad isn’t there. But, could play a role as a tool used to access increasingly cloud-based tools.
I’m optimistic about iPad. I can’t wait to have one again (been without one for 4 years, for financial reasons).