Works very well for the streams I like. Between Roku, Amazon Fire and Blue Ray, Roku works the fastest. MLB Premium also works the best with my Roku, although it still buffers too many times. The Fire is the worst for Premium.
I would've given it a five star but the only problem I have with the Roku is once I downloaded the remote to my phone the remote control doesn't work. So if I am not home and someone wants to use it they can't until I get back. It doesn't work when I am there either. Otherwise I love the service I get from it.