This is my primary study app. There are a few minor complaints I have:
Occasionally SabbathSchoolPM doesn't match the printed quarterly and is missing lead in verses for the day. I have a few other apps, usually they are missing the same, so it's not just SabbathSchoolPM that has the problem.
One of the things I like is that it includes related writings of Ellen G White after the study. Unfortunately after a new quarter begins sometimes it takes a few days for the writings to appear. But since the other apps I've found don't include the writings at all, and it's usually updated within a day or two, this is minor.
My last complaint is that the context verses are not included in the bible references. Some of the other apps include the whole chapter and highlight the subject verses. This gives the context for what you are reading. The flip side of this is that when several verses are together, they all appear in one window, allowing you to read everything without having to tap each verse (which is especially nice when using a small screened device)
Again, these are minor complaints overall.
Things I like are the simplicity of SabbathSchoolPM . From the home screen, just tap of "Read" to be taken to today's lesson.
There are several bible translations including the KJV, NKJV, NIV and others.
There are also several additional included studies (for teachers, kids or teens, etc.)