To be honest, this is nothing new. There have been any number of apps that pulled content from free ebook websites like PG, Feedbooks, Smashwords, and so on. Those free apps have been around since Stanza launched in 2008 and there are even paid apps that will charge you for the privilege of reading free ebooks.
But I like this one because it combines a number of legit free ebook sources into one search engine and because it is only a search engine.You don't have to read ebooks in this app; instead you can use your preferred app.
In this day and age there is no reason to lock someone into using a particular app. That unfortunate restriction should have died out with Windows ME, but in the mobile world it has managed to hang on for far too long.
To be fair, the single app restriction held on more because of Apple and their design of iOS than because of app developers. Early versions of iOS (and this is still true) made it very difficult to share a file between apps. Difficult? No, I think impossible would be a better word. Reading the technical explanations of how people bypassed the restrictions was quite interesting at the time.
And Android isn't much better. I still encounter the occasional hiccup while trying to open an ebook with my preferred app.
But at least that is beginning to change, and this app is a sign of the changing times.