I was learning Blues piano, and still am, but have found the Alfred’s “Simply Beethoven” or “Simply Bach” books just fine. The Simply series have different arrangers, so there will be variances in the level of difficulty even within the series.
Maybe they are “dumbed down” but the music is put into easier keys do you don’t have so many sharps and flats to deal with. They capture the essence well, let’s say “Moonlight Sonata” sounds like it, but you only have one sharp to look out for.
Sight reading is slow going for me, but I have found to try and lock in the right hand more to memory and focus on the left. Reading both simultaneously can be a challenge. I never studied as a kid, so it’s tougher 
The “Simply Joplin” book is harder than the Beethoven one, I can’t jump around as much, and it requires more focus. I ordered the “Simply Bach” and I better stop, since time is always a factor with any endeavor.