@pratik Annotating, taking notes & doodling is the primary use case and where it shines. Getting DRM-free ebooks and PDFs on the reMarkable is easy. On Apple devices, you install the app and get a send to reMarkable option in the share sheet.
For locked-down books, you must get rid of the DRM first. It's relatively straightforward with Calibre and DeDRM_tools but much more involved than borrowing a book via Libby on an iPad. And you might commit a crime when circumventing the DRM protection, depending on the laws where you live. 🦹