I am buying an Apple TV, soon.
Apple does not do everything well, but what they do well is integrating their products. With Apple TV I will be able to use the features of the iCloud, iTunes Store, games, apps, Youtube, Netflix and Airplay, etc. My three year old who is good on the iPad will now be able to take control of the TV. Be warned that Airplay mirroring only works with Mountain Lion and not all iOS 6 devices but does work with iPad2 and 3 and iPhone 4S and iPhone 5. If you don't have all the Apple gadgets that I do, get whatever.
Here is a comparison between the Roku and Apple TV: