I have a kindle, actually we have 3 in the house. I also have an Ipad. My hubby loves to buy me toys like this for my bday. I have a generation 1 kindle and it still works wonderfully. The kids each have one now and they love them as well.
Yes, they are very user friendly. Even if you are not a techie, soo simple to get going on them. And if you have any problems, you can call them and get a real person to talk you through the issue.
I have an Ipad as well. If I am just reading a book, I will pick up my kindle. It is soo much lighter and easier on the eyes for long reading.
Yes there are tons of free/cheap books out there. That is mostly what my DD gets on hers...she does not like to spend money on the books. My daughter, son and I are on the same account...so we share our books on all of the devices. I can also get to those same books on my ipad or my phone. So very useful in that manner.
Have fun. :)