If you're a theological student or a pastor and don't read any theological journals, Themelios is the place to begin. Unlike some other journals which aim more at the professional theologian, Themelios is specifically aimed at pastors and students, and so the content is always accessible and informative. Plus it's edited by D.A. Carson. What's more, it's available for free online!
Each issue also has a large number of book reviews to help you decide what's worth reading.