The Color Purple touches on many truly difficult and important subjects; domestic abuse, slavery (modern & traditional), mysogeny, rape, trust and gay relationships. Quite a lot for a musical to get through in one evening. The songs are very good but I didn't come away humming anything - it is not really that sort of musical. In fact, for me, the production hadn't really made up its mind what sort of musical it was; the three women in the Greek chorus were fab but out of keeping with the true life sections and near operatic passages. Voices were, at times during dialogue, very quiet for the size of venue and the "club" lighting was distracting and out of keeping - in fact the set seemed to add little to what could have been a more intimate and touching production.
Singing voices were universally good, I especially loved Bree Smith's Shug Avery who had a lovely tone and Jimand Allotey as Squeak who (purposely) did not! Whilst some of the characters' emotional shifts, especially anger, appeared to come from nowhere the storytelling was sensitively done.
To care about the issues you need to engage with the characters, but for me, every time I got close I was distracted by production issues. Your mileage may vary and the audience seemed carried along so maybe it was just me.