Former teacher here: I taught open project classes, one class with old school desktop computers and one with iPads. The difference between the two techs was immense.
Desktops are made for productivity. You have a mouse, a keyboard. It's easy to type weird characters, copy/paste, save, use office suite, etc. Yeah, you know that. You're HN.
Ipads are made for consumerism. They lack a good typing device (I admit this specific point is more opinion), menus for more complex tasks are not so easy to use. With an iPads (or a smartphone) you typically scroll, scroll, scroll. Simply saving text students wrote on ipads was such a tedious task for them. I feel most smartphones fall in this category, and as such, I think they have no place in the classroom.
Internet in the classroom? Please more. Internet usable only through touchscreen? Never ever.