She's an avid reader
She's ok with text messaging and internet usage
She's always wanting to get rid of things, so this would kerb the massive influx of paperbacks from charity shops
She travels by train a lot and a kindle's lighter than a hefty book, yeah?
OR
Will it ruin her charity shop book-buying hobby
Will she end up having to spend loads of money on ebooks or is there lots inexpensively available?