No doubt that InDesign is very capable. If anything, it is an overkill for a simple ebook.
Better to have to much power than not enough.
Paradoxically, one would appreciate the power and myriad of features of a fully fledged page layout software more for the design of one page advertising flyer rather than for a simple 300-page ebook. Except perhaps for file export format, where Indesign can handle a number of output formats.
I have used both Quark Express and an early version of InDesign, even PageMaker for paper versions of books, however for a simple book page layout I never needed a lot of bells and whistles. Over the last twenty years, I have created about ten small color photography books both for large print run CMYK lithographic printing and small-volume of Blurb print on-demand books, typically with one or two pictures per page, plus a caption or a short paragraph, with quite a few two-page full-bleed spreads showing panoramic images. For these types of printed books, even a 15-year old page layout software or the latest Blurb program will do just fine.
For my planned ebook project, I'd like to keep it again simple. For each page, I envision only one or two images accompanied with some text above or below, plus occasional URL link or some video/animation widget. My dilemma is whether I'll have to constrain the design to the fixed page layout or whether the software will properly handle sensible pagination, free-flowing text and different reading devices.
Nowadays, the ebook options and challenges differ drastically from a paper book version, especially when taking into consideration the responsive or adaptive format display. Not only that, but with the availability of 4K monitors and iPad Pro tablets one could now lay out the ebook quite differently than for simple EPUB or PDF format displayed on a smartphone. Let's hope that we'll soon see new developments and more flexibility for the large display ebook formats, enabling to see features as two page spreads and properly sized panoramic images.