Sure it's an action masterpiece, but is this something worth beating more than two times?
This is all and good, but does it make for an endearing and long lasting gaming experience that you can come back to time and time again?
No.
There isn't the amount of technical gameplay of Ninja Gaiden, where it makes the game worth playing to go back and see if you can get through sections of the game without getting hit, without using health items, and while stringing together kills. Nor does God of War have the gameplay variety that gives the game something fresh and something worth going back to after it's beaten, ala Devil May Cry 3. The story has its interesting details, especially about Kratos' past, but it's simply an outline to a full-fledged story at best.
This game doesn't even have a good amount of extras to make a player want to come back and play the game through. There are videos about the effort that went into the game, and a fairly interesting little museum of character designs that didn't make their way into the final game.
I don't hate this game. It's a solid game in a resurrected action genre. It's even a standout title because of its gore and its visceral gameplay. But this game has trouble making a 7 hour playthrough not feel like it lags at the end. How can that translate into long term playability?
***OVERALL***
It's absolutely worth playing. But $50 cold hard cash?
If you have to own it, it's worth the wait to get it as a Greatest Hits title.