I purchased a Playbook for just that reason.
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It functions as a e-reader and gives all the extras that you get from a tablet.
It is also at a bargain price as it is out of favour, although it is a solid well-built piece of kit.
[Got mine off ebay new for £149.99 inc taxes/vat (32GB model)]
The reviews on the interweb are mostly out of date and negative.
Yet, the hardware spec is excellent and the latest OS update to 2.x is very good.
With a bit of luck more is to come but even as it stands it is much better that a Kindle or similar as it has functionality beyond just being a e-reader.
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Hope more people see the bargain it is.