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.
Lots of excess civillian deaths, kidnapping/ransom schemes, illegal drug trade. Maybe I'm a lib or whatever, but even if they're comrades their methods aren't very palatable (and I would guess many Colombians feel similar, I'd like to hear from a Colombian leftists or two on the topic though of course).