Whether for documentation (digital timesheet), whom I send immediately after a digital signature to the billing e-mail, as the logbook, the communication within the company or even for remote maintenance with TeamViewer Pro. All this and much more I do today with my iPad. We now have 5 units in the house and no one wants to give it back.
Sure, a smart phone is handy, a notebook can do more, but my iPad is ready to go and do just fine for my purposes. So far I have not found a limit and my Tecra A11 is since unused in my docking station at the office.