I don't think NOW TV is competing with other streamers since you have to remember that dedicated NOW TV streamers are also Roku manufactured with custom software that allows you to have a more enhanced NOW experience. As a result, whilst some of the Roku features are present like using their app to control the stick/box, there will be some things that have been omitted.
The price point difference also suggests this, that they've kept the devices as basic as possible but to ensure that everyone can get the NOW experience on their TV. Imagine if NOW did an app for the Fire stick it would be a popular choice amongst owners. I used a Chromecast for a while but the playback experience is nothing like using the dedicated NOW hardware.