The Roku and Logitech Review allow you to stream content from the internet to your TV.
I have the Logitech Review with Google TV and buy movie rentals from Amazon for 4.00 per rental. It also allows me to surf the web with Google Chrome on my TV as well as stream content from other computers on my home network, i.e.; photos, videos, and music that is stored on my desktop , netbook, notebook, tablet... etc.
Part of the reason for bad reviews associated with both these products was the price and lack of content associated.
The Logitech Review was selling for 180.00 just a couple months ago and now sells for 80.00-90.00. The content for these devices is improving as well.
I personally like the Review becase it comes with a full keyboard (wireless) and gives me the streaming capabilities from my local network as well as the internet. I also like haveing the web browser.
It also works on the "Android" platform and therefore has a familiar feel and function. You can get apps for it, but most are not all that good.
It also lets you surf and keep a picture in picture of your TV,