Showtime has decided to take a different approach to Roku than did HBO with their HBO Go channel. HBO provides on-demand access to their large library of movies and series, but only to those Roku users who subscribe to HBO through a cable or satellite provider. Showtime, on the other hand, has made their channel available for free to all Roku viewers - but the content is much more limited. The Showtime Roku channel is more in line with Disney's Roku channel, acting as a promotional channel in an attempt to entice viewers to pay for more content via non-Roku avenues.
Click here to read the full RokuGuide review of the Showtime Preview channel.