On the heavy pistol list the Ares Viper is the second cheapest gun, with the cheapest being the roomsweeper. It has a healthy 9P damage base (Better than the Ares Predator), can lay down bursts and long bursts, is inherently silenced (allowing it to take a gas vent accessory and be both silent and sustainable in a longer fight) and has the largest clip capacity of any heavy pistol in the core book, double that of its nearest contender.
Unfortunately, it also has some serious or even crippling issues.
Firstly, its accuracy. With a measly 4 as the weapon's base accuracy the gun has gone from an assassin's tool to a silent spray and pray machine. While this isn't necessarily a bad thing, it really changes the role of the weapon in a way that I'm not entirely sold on as being an improvement. While this can be somewhat addressed with various aiming accessories, it'll never be as accurate as most of the category.
Secondly, its armour penetration is as dismal as you would expect for flechettes. Unfortunately, the corresponding boost to base damage isn't really enough to put it in the same league as an Ares Predator against any foe with even a hint of armour. In 4th edition the damage increase was larger relative to other guns in its class and called shots could be used to bypass enemy armour, once again circling around to the idea of an assassin's weapon. Here, its straight out damage is inferior to the defining weapon of the class even without factoring in special ammunition.
Thirdly, it cannot use special ammunition. Not only does this mean it is rapidly outclassed by other guns using the right weapon for the job, but it also means that you cannot load it with non-lethal rounds if you have to take a foe alive. On the other hand, it also means that if your foe is wearing an armour jacket you are literally unable to deal lethal damage without both an aiming aid AND a called shot for extra damage.
Finally, its specialty (the ability to fire bursts and thus reduce the enemy's ability to dodge/hit multiple targets as a simple action) is outdone by the cheapest gun in the class, the Remington Roomsweeper. Though the Roomsweeper is incapable of firing bursts beyond a semi-automatic burst, when loaded with Flachette rounds it uses the shotgun rules. This means that when used on semi-automatic mode with a narrow choke it is already inflicting a -1 modifier to dodge to the Sliver gun's -0. A short burst takes the Sliver gun up to -2, but because of recoil the roomsweeper will rapidly outclass you at endurance. When the roomsweeper starts playing with the choke settings this becomes far more pronounced, with the roomsweeper able to attack multiple foes with a single shot while inflicting a large dicepool penalty AND not forcing the attacker to split his dicepool or use his free action. If worst comes to worst the Roomsweeper can actually lay out a superior dodge penalty to the Slivergun by firing a semi-automatic burst at wide choke, inflicting a -7 penalty instead of the long burst's -5. To add insult to injury the Roomsweeper is capable of loading any ammunition type a normal gun could in a pinch AND is cheaper.
Final conclusion: If you need to take a pistol to gun down a horde of critters, the Slivergun is a solid choice. If you are coming up against semi-competent opposition, this gun is one of the worst choices for sidearm. A pity, as it's also one of the more interesting guns in the game.
