I take issue with some of their political objectives that aren't related to racial equality, and more specifically, I take issue with their support of anti-Israel boycotts, which I find a tad hypocritical. Obviously the Israel situation is immensely complicated, and for the record I don't agree with everything the Israeli government does, but I do not support the hypocritical BDS gang, with their bullying of (for example) musicians who want to play in Israel, or Israeli film directors, etc. But that's a long complicated issue that I haven't got time to get into here. The point is, BLM (the organisation) largely supports BDS type movements. I don't.
The sentiment black lives matter obviously I agree with.