Piiskopi viewing platform is one of the multiple observation platforms that upper Old Town of Tallinn can offer. Piiskop in English means bishop and the platform is named so because there is a Dome church (Toomkirik) nearby. The platform was renovated a few years ago and I think right now it is the most beautiful viewing platform in the upper Old Town. I recommend visiting it because it is bigger than the Kohtuotsa viewing platform, but at the same time less touristy and the views are also good.
You can sit on a bench and enjoy the sunset, and actually there are more beautiful sunsets on this platform than on Kohtuotsa. Basically, from Piiskopi platform most parts of western Tallinn can be seen and the view of it is also not as hackneyed as the view of eastern Tallinn with its skyscrapers and the lower Old Town of Tallinn.