Yes, it was tedious using up my voucher money - ordering book by book!
The app is very unstable, have to manually create a bookmark after each reading session, or it goes back to earlier bookmarks on re-opening the book. Also crashes quite a lot on opening the app.
If there's one thing the free vouchers has taught me, it's that Samsung Movies store and the WH Smith store are currently unfit for purpose!
On the other hand, I've had no problems with the Amazon Kindle app and their ebooks, so I know what I'll be using in the future.