personally i tihnk modern cellphones are remarkably clunky devices for anything other than reading books and gps. they aren't even very ergonomic as phones, they're annoying for web browsing compared to laptops, and they are definitely not satisfying to use as controls for physical devices.
This sums up what i feel. What do you think about it? Are smartphones inherently wrong?
Ergonomic as phones? I would imagine the actual "phone" part is now a secondary feature at best to most users.
Annoying for web browsing compared to laptops? Yes, but it's also pocketable while a laptop is not. You can't exactly whip out a laptop to browse the web while standing in line at the DMV.
Not satisfying to use to control physical devices? I agree, but the touch screen UI lets you able to control multiple physical devices instead of having a separate physical remote for every device.
Again, with the caveat of using available current technology, I don't see how you can make smartphones better than they are now. It's a jack of all trades, master of none device.