I love my Kindle! It is much easier to take with you than a stack of books.
If there aren't pages built into the ebook it will show the % of the book read.
On my Kindle (a basic black-and-white model) you can change the type size, but that also changes the number of pages in the book. That makes page numbers written into the text inaccurate, while the %-read display stays the same regardless of type size. That's good for those of us with aging eyes!
I really like how long a battery charge lasts (with the Wi-Fi disabled). A long multi-leg airplane ride is no problem, unlike the limited battery life on a laptop. The fancier models (with lighted color screens, etc.) may not do as well as the basic model when it comes to run-time.
If you get one, be sure to check out the selections at Project Gutenberg. They have many classics and out-of-coyright books available for electronic readers, free of charge.