FatFreek2005: If you are looking to cut down on your sat TV bill or simply increase the hub of your entertainment sources, streaming devices are a must have. Not only will they improve content available to you, they also offer flexibility of where to watch desired content. For instance, you can simply plug in a Chromecast dongle into the HDMI port of an older non-smart TV (with no apps) and be ready to watch stuff from Netflix cast from your phone or tablet in your kitchen while you cook. This is definitely cheaper than getting another DirecTV client which you'd have to pay monthly subscriptions for.
That said though, the best content will require subscriptions so I guess you will have to do the math on what you really need. Most TVs and blu-ray players these days come pre-loaded with the most popular apps to stream content (Netflix, Amazon Instant, Hulu, YouTube etc).