I bought a tablet last year partly so my wife could get her mail and buy shit she doesn't need on the web, and partly so we could backup our photos from our DSLR when we're travelling.
It does both, but isn't very good at either of them. I've yet to find an Android file manager which lets you only copy files which have changed, there's no shift-select equivalent, so if you want to select 500 photos in a directory of 1000 you either have to select 500 photos one by one or copy all 1000, overwriting the 1000 you have already copied.
It goes on: Android is half-baked and half-finished. You can do a lot of stuff, but it's incredibly difficult to do any of it. I'm typing this on my laptop, and can do so about 10-15 times more quickly than I could on a tablet, let alone a phone.
As for ipads, they don't even let you copy anything to internal storage, and there's no option to add external storage. What's the point in that?
There's a place for tablets, certainly: the size makes a huge difference and for the computer illiterate who don't know what they're missing with proper computers they're probably great.
As for planes, I tend to get the overnight flights and go to sleep. Best way to pass the time.