Full disclosure, I use the main Reddit app. I don't think that I've ever installed a different app. That being said, I think it's actually pretty crazy that Apollo is #10 (in News). It's not clear that being 8 spots higher is that much of an accomplishment considering the site itself is constantly pestering you to install it, and the Reddit app can be used completely for free vs. the Apollo app requiring you to pay (which may by itself explain the .1 difference in reviews). Actually, I just went to the AppStore to read the bad reviews, and sorted by "Most Critical", and from a very short cursory glance it seems that most of the new bad reviews are from people who are angry that they bought a lifetime subscription and the app is now shutting down. It's kind of impressive that it is still at 4.7, honestly. But more importantly, I think this also means that the 4.8 vs. 4.7 comparison isn't necessarily representative of the sentiment a month ago.
I am in basic agreement with everyone that the core app sucks. It just means that I use Reddit less in general instead of going out of my way to fix their problem for them by finding an app that works. That is another failure case that isn't really considered: there's a bunch of opportunity cost just in people who have a bad experience and then switch to YouTube or whatever.