This does seem pretty cool. I like to read on my kindle paperwhite, and this looks similar
Pros:

• Less Eye Strain
• Big "cool" factor.
  Cons:
• A $99 USD case seems steep, a Kindle Paperwhite is less expensive, and in my experience lasts several years, likely longer than you'll keep your phone.
• May need a new one if you change phones.
  Summary: Really cool if cost is no concern for you, but I'll keep my Kindle Paperwhite and forego the extra expense.