Half Life: Opposing Force

People say:

• "I have to say how disappointed I am with Opposing Force. Why was it so short? I'm not saying it wasn't hard enough (the bits in the dark tunnels where you needed night vision scared the hell out of me at times), it's just that I got it for Christmas and I had finished it within four days.
• "A good weekend of entertainment, but Opposing Force doesn't have quite the sparkle that one would have wished for."
• "The game is fantastic in every sense of the word. My social life has already gone down the drain. Valve should be proud of the folk at Gearbox and what they did."
• "I installed it at 2pm on Boxing Day and completed it at 10am this morning (27th). This is surely the crappiest and easiest game ever. And as for those stupid, stupid alien weapons..."