I recently purchased a ROKU XD (one step below ROKU 3). One thing I want to warn you about. When the AD says 650+ Free Channels, it is a bit misleading. Yes, you can get those channels for free IF you have an account setup. So, if you have a HULU+ or Amazon Prime account, you can "connect" those accounts to the ROKU box. Everything you can watch on those accounts can now be viewed on your TV through the ROKU box. Very nice feature.
However, you must PAY for those subscriptions. In addition, ROKU does offer the ability to PAY for subscriptions to channels like FX, Bravo, etc. I am sure many people will tell you that I am wrong and you can get FREE channels by doing this or that, but if you want to avoid the "gray areas" of trademark laws, you will have to pay for those channels.
Don't get me wrong. I really like the ROKU technology but if you are looking for a replacement for your cable/satellite TV then ROKU may not be the right choice. I do not have any cable or satellite service. I came from just watching TV with digital "rabbit ears" meaning I got ABC, NBC, CBS, FOX and PBS. Talk about Channel Deprivation!!! Lately I have been watching old seasons of some of my favorite TV shows using my Amazon Prime account.
My latest obsession is "Sons of Anarchy".
Hope this helps.