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.
What is worse than the actions of Peta for their publicity is the industrial media complex. With peta you don't make money. Advertising for companies, for meat, for repression and hierarchy you do.
Any critique of peta without looking at the capitalist system of advertisement and its connections to the productive system and the ownership of the means of production is lib propaganda.