Jacobin is by and large good. As another commenter pointed out, they give space to all kinds of lefties. That leads to some pretty lib takes now and then, especially in the online edition. If tendencial purity or hard-line anti-electoralism is your chief desire then sure, not for you. But I think generally it's good for promoting left unity, discussing historical and current events, propagating trade union news &c. It's probably the closest we've got to a mass left publication in the US.