There also is an iPad mini which is probably better suited for people who merely want to read books on a tablet. And there's the Kindle Fire and lots of other devices, some of which have been mentioned above.
I find the iPad to be absolutely fantastic. The screen is pretty much the best you can get. The GUI is intuitive (to me). There are many, many brilliant apps, the bookstore has plenty of free books that you can just put in your iBooks library—especially if you're into classic literature, you're in for a treat as they have hundreds of those that you can download for free, from D.H. Lawrence, to Edgar Allen Poe, to J.W. Goethe.
It's definitely a high-end tool (but so are others). For me it was an absolute no-brainer to get the iPad because my desktop, my laptop, and my smartphones are all Apple products anyway.
Another thing I like is the fact that there are so many apps I only ever need to buy once and can use on several devices.
Whether it's worth the price? Its worth is always determined by the critieria you set for yourself. To me, it's worth it because I have these criteria:
- Is it of great quality and can I use it for the next couple of years?
- Are the apps of high quality?
- Is it easy to use and intuitive?
- Does it save me time (configuration, maintenance, etc.)
- Is it aesthetically my cup of tea?
And, not to forget, it's rather handy to own one if you build things for the web, just like it makes sense to have at least one mobile device that runs on Android and Windows until the web offers solid means with which you can test your work on devices you don't own—There's a lot being done in that regard at the moment, which is great.
But that's getting off topic.
For reading purposes, I think pretty much any tablet will do. If I were you, I'd read up on tablet comparisons and reviews, then go to a local store and check the various tablets and see which one is meets your requirements best.