hmmm, it depends on how much you read really. I have the original nexus 7 and just upgraded my kindle to the new paperwhite. The nexus will definitely do the job – you can download the kindle app and sync your e books with amazon just as if you had a kindle. The app works well and there’s obviously plenty of room to store books.
that being said, i still have both because the kindle is a lot better at this than the nexus. The nexus will do the job, but the kindle does it a lot better. The e-ink set up is great, there’s no glare even with the paperwhite back light on, its much much lighter and also works far better in bright sunlight. I’ve used the kindle by the pool on holiday and it works far better than a nexus in this situation.