Pros: They have the voice actors
Cons: Poor graphics, poor controls, short, unfunny, numerous technical issues
Gameplay wise it's a mostly standard 3rd person shooter. However shoddy controls and even worse hit detection bring it down significantly. You'll often have an enemy lined up for a headshot only for it to not hit and when the enemy moves you'll see the bullet somehow hit behind him in the environment. The poor level design does nothing to help. The games first level consists of fetch quests, the second a shootout with the Amish where the lacking hit detection becomes overly apparent and not to spoiler the rest of it but it only goes downhill from there. The only bright spot in the entire game is the chicken fight level where you play as Peter and continue the legendary fights from the show. This comes very late in the game following a terrible Alien parody that's as rotten as the eggs in the level and just before the final boss. If you do choose to play this you won't have to suffer too long as the game clocks in at a paltry 4 hours.
Graphically the game tries to copy the shows art style but fails miserably. The result is a poor looking cel-shaded game. Many of the characters look off, including Stewie. When one of the two main characters of a licensed game looks that bad something has gone terribly wrong.
Sound is the only part of the game that isn't a complete failure. They have all the voice actors from the show and the music isn't bad however the lines they have the actors spouting are not funny and don't add to the game. The script certainly lacks the wit and humor of the show.
Overall this was one of the worst games of 2012 and should be avoided at all costs.
If you're not a fan of the show there's nothing here for you, if you are then you'll be insulted by the poor quality.