I think it depends heavily on what you're using your computer for.

One of my parents owns both an iPad and a laptop, and the laptop barely sees any use anymore. He's got a keyboard case, and, while I hate that keyboard, he's perfectly happy with it. Email and browsing are about equally good on iPad as they are on a computer. Browsing might even be better what with the no flash. It plays video games & runs Netflix, and that's about all that matters. I don't think he cares two beans about multitasking. The iOS office apps may or may not be good enough; the last time he cared about document editing was pre-retirement so I don't know that he's really put them to the test.

Challenging? Nah. I'm pretty sure he settled into it because, for him, it's easier.