This is a useful Roku feature but it has limits. First, the good stuff. I have over a dozen TV’s in my house and the Roku has proven to be a very cost effective way to get good content to all of those TV's. The fact that the Roku has the ability to mirror/stream material from my Mac is a bonus. Second, it’s relatively easy to set up the Mirror app and while it’s not as smooth as Apple Airplay or mirroring to an Apple TV, it is much less expensive than an Apple TV so I’m not complaining. Now the primary limitation. There is considerable lag in streaming and mirroring from your Mac to the Roku through this app. I estimate about 4 seconds lag and I have a very solid network connection. This is definitely not a viable solution if you need your Mac (audio or video) and the TV (audio or video) in sync (e.g. if you’re presenting something). If you don’t need your Mac and TV (audio/video) in perfect sync, however, this is a good way (and an inexpensive way) to stream/mirror video to a TV screen. I have, for instance, used this app to seamlessly stream security camera footage (audio and video) to multiple TVs around the house. It’s not of the quality of solutions such as Control4, but it is much less expensive and truly does get the job done. My 4 rating is based on the fact that it does what I need it to do but if you’re looking for a streaming solution that keeps everything in sync (e.g. if you’re planning to use this to make presentations), don’t waste your time with this.