I bought an iPad Mini-4 because my Mini-1 can't run the newer versions of iOS required by many apps.
So ... what to do with an "antiquated" Mini? It is my dedicated Marvin eReader. Hopefully, my Mini-1 and Marvin will last "forever", or at least outlive me!
Marvin 3 is not perfect, but IMHO it is still the best ePub reader available.
@MusPuto: As you know, M3 has MANY features that are not easy for some new users to find. So, I check out the posts to see if I can help out a newbie. Probably many M3 users do the same.