Pretty minimal story compared to Half-Life, but Opposing Force excels in Combat. The additional weapons and mechanics are a blast. Playing as Adrean Shepherd gives you a new perspective of black mesa incident. It kind of feels nice to visit the same locations again those you have seen in the original game. Even seeing the events of OG game happening from a 3rd person view.
This game might have got overshadowed by the OG half-life's impact on gaming industry, but this one is what I enjoyed more.