From what I know, their main cause is overall just and they have done good work infiltrating places with hidden cameras and recording/exposing animal cruelty...
...But their publicity stunts, probably the big thing they're known for these days, are almost always stupid and imo do more harm than good by turning potentially sympathetic people against them, and possibly by extension animal rights.
Also the person (Rich Berman) behind 'PETA Kills Animal' also funds a think tank called 'Center For Union Facts' . Which argues that 'argues that unions are corrupt and bad for workers.' Not say I've made the deep dive into PETA but that should make one immediately suspicious.