I absolutely LOVE the Faber Piano Adventures curriculum. My pedagogy teacher in college said, "Never believe anything until you hear how it sounds." Now that I have taken a few students through this curriculum from beginning to end, I would say it sounds nothing less than beautiful. My students are extremely well equipped for intermediate classical literature upon graduating and they extremely independent learners. It's almost like they teach themselves at times.
I typically alter the teaching order of the primer level to get them reading on the staff a bit faster. But all in all this is a fantastic curriculum! You will not find a better reading approach than the Intervallic reading Faber introduces... while still having songs that sound familiar to the ears.
A few tips:
Synchronize the books... make sure you at least use the technique, lesson, and theory... they are not complete without each other... and do not go ahead to a new unit until you are ready to move in all books. The only exception is just using the lesson book if you have a very gifted student that can move through more quickly, but even then, practice never hurt anyone.
Supplement with basic technique scale skills that you teach by rote:
Primer: white key five finger patterns
Level 1: black key and minor five finger patterns and hand over hand arpeggios
Level 2a: white key one octave scales and Cadences (this is extremely important as this concept is a huge challenge in level 2b if they haven't already played it)
Level 2b: black key and minor one octave scales and cadences
Level 3a: 2 octave arpeggios and 1st and 2nd chord inversions
Level 3b-5: they are ready for any popular scale skills book such as Hannon
Also sometimes it is like a magic trick to have a student play through one or two of the supplemental series of the level they just graduated before they move on to new books. It cements the old concepts and gives them a sense of mastery because they will learn fast.