In the app, searching is abysmal. There's no way to specify the type of keyword you're searching for, so if it's an author, you'll probably have to wade through a sea of wildly irrelevant results to find that maybe they don't even have anything from that author.
I grabbed two different versions of Mary Shelly's Frankenstein, both of which the website proudly stated were included in my subscription. Neither was a truely optimized ebook. More like PDF images, so the text or pages didn't scale.
The reading experience on the app is sub par. No options for font type, size, or color; no background options; or margin options. No "night mode" or similar.
There's also often not an indication that a book is just a preview on the website. I added Cormac McCarthy's Child of God to my library, and the app told me that it wasn't available in my country (US), but I could read it on the website, but I discovered it was a preview only.
Related to that, when searching on the website, it seems to prioritize purchase-only books over subscription books. I understand the why, but it's really frustrating to have to start scrolling to get to what most people will be looking for.
Then there's the trouble with having to wade through the sea of user-uploaded content. It seems like there should either be a separate app for the subscription portion, or at least a way to search ONLY that.
All in all, I really wish this was something I could see myself paying for, but right now, I think it's kind of a mess.