Before, it was between phones- which were small-- and laptops-- which were big. But the Air is becoming a lot more mainstream, laptops overall are becoming knife thin, and phones are getting bigger.
I think the iPad was meant to replace the PC for most use cases-- e.g. the email, web surfing etc.
and I think it's been somewhat successful at that. But like pcs people don't replace them every year (wheras phones seem to be replaced every 2-2.5 years).
Now with the Apple Watch, the phone has moved up to be more tablet sized, and the new smallest form factor is the watch.
Will the iPad move up and become more like a PC?