I'm sure at one point they were a thinking man's newspaper. At this point they're just fan service for people who have drunk the koolaid but can't stomach Fox's mass market approach.
The opinion columns slant very far right, and I'm sure Murdoch has played some role in that. I subscribe to the Journal and am outraged every time I see them. But, it's good to see what other people are talking about. It does you no harm to read an opinion column that you vehemently disagree with. I'm sure people feel the same way about opinion columns in The New York Times, which I also read and tend to agree with.
My TL;DR here is that if you are interested in the news, you should get it from a variety of reputable sources. The Journal has proved over the years that it is reputable. I haven't seen anything recently that would change my mind. I have friends that get all their news through social media and they are constantly outraged based on pure misinformation. If they read the Journal, they'd have a much better understanding of the facts. (Same goes for the New York Times, or Washington Post, or The Guardian.)
The WSJ is owned by Rupert Murdoch. The credibility of their newsroom begins being compromised by his owning it. He will destroy its credibility utterly by selling it for politicial influence in news reporting. Just as he has everywhere he has bought media. The particular example of compromised credibility that comes to mind is the Times of London which is now Murdoch propaganda (all be it vastly more polite than fox news) where it used to do credible news reporting. Times reporting now can still be excellent but has a "be cautious" flag on it that it used not to have in the days prior to Mudoch. The man has become vastly worse in the past couple of decades as has everything he touches.