Those that raved about it doing wonders may have been motivated by the placebo effect.
I assure you there was no placebo affect. The ad balancer is the only thing that was able to eliminate all the spammy ads, such as download buttons, horoscopes (despite blocking the sensitive cat), cider vinegar ads and a whole lot of other crap. Whether or not it increased, reduced or changed nothing in terms of earnings is hard if not impossible to say, but it didn't hurt.
Since mid May when the feature stopped working my site is once again flooded with crap, and I am back to spending hours reviewing ads in the hope of mitigating any negative impact of showing my users this spam. Most of which comes from Ad-Words.
Now the question is when will it be back up and running? Or, is the question will it ever be back?
The other question is, is it worth it to set up a DFP account to use DFP to achieve the same goal as Ad-balancer?
Let me not leave out the other big change, that is ad-blocking in Chrome and the associated Ad Experience Report in GSC. The "poor experience" ads are the ads that were previously being blocked with the ad-balancer, now without the feature these are impossible to block. So what comes next, we get all are ads blocked by Chrome. Because A- Adwords allows the spam, B- Adsense provides no effective tools for blocking it. As you can probably tell I am little p'ved by all this.