If you enjoy the genre then Viper will keep you entertained for a while, if you want a cerebral challenge, get Chessmaster 3000. I recommend you hire Viper before you buy. Don't get me wrong, I love shooters and Viper is no exception. I love being able to sit down, turn on the Playstation and turn my brain off. Mindless shooting and pretty explosions are good for a bout of aimless destruction.
Viper pulls off the 'shooter' game very well.
All of the elements for success are there, lots of enemies, lots of power ups, lots of options and lots of music and sound effects. The only real let down in the game is the bad clipping and on-rails gameplay style, which means you have no freedom of movement.