It wasn't. It was a bad run-and-gun game of this generation. Stealth games usually involve some degree of hiding.Sigh, why is MGS4 the only good stealth game of this generation.
I know what the answer is going to be - the classic fanboy "but the great thing about this game is you can play it however you want" (Metal Gear Solid Bible, Apologetics chapter 14, verse 9). Sorry, but a Hollywood-style "mow down rows of enemies with a huge arsenal of guns and a rocket launcher" action game is still an action game even if you can choose to hide around. I can choose to race those fast little buggies around in Battlefield 2, I guess that makes BF2 a racing game in your eyes.