That's the case no longer. The cabin of the 2014 SRT Viper is well-designed, well-upholstered, and quite comfortable, considering the Viper's rather hardcore focus on performance. The new seats look like they're straight out of a Ferrari (because they're made by the same company), the new materials are universally upgraded, and the design is modern, if still a bit minimalist. The massive touchscreen interface in the center stack looks and feels as high-tech as it is high-res.
In GTS models, the luxury factor can be increased significantly, with Nappa leather and carbon fiber accents available. Whichever trim line you choose, however, the Viper's cabin is, ultimately, a sports car cabin: small, cocoon-like, and low to the ground. There's a fair bit of road, wind and engine noise, even at lower speeds; it becomes a roar at highway pace.
Storage space around the cabin is limited, though there are several small bins and cubbies. The trunk is almost sedan-sized at 14 cubic feet.