Frequently well intentioned but often misguided and counter-productive. Like many similar organizations, their strength lies in members who are "on a mission," and by that, I mean people who feel they must prevail at all costs, and are incapable of recognizing that there is a legitimate argument to be made on the other side.
And also, these organizations are very well funded because they work on the principle of spreading misinformation in and amongst their factual claims, inspiring fear and revulsion, and getting people to send in money which in turn goes to an extremely well paid leadership cadre whose main purpose is not to protect animals, but instead to inspire more fear and revulsion so that people will continue to send in more and more money.
This is unfortunate because there are bona-fide reasons for PETA to exist, and PETA has inspired some good work.