There's a lot of overlap between what's on Netflix and what's on Hulu/Amazon Prime/etc, but Netflix Instant is absolutely worth the $8/month. We haven't had cable for eight or nine years now, and don't really miss it. The upsides:
- Did I mention only $8/month?
- The content on Netflix Instant rotates enough that there's always something new to watch when you just want to sit down and watch something
- I really like being able to make a queue of "this stuff looks interesting" and essentially mark it for later
- You can stream Netflix to multiple devices at once, so I can be watching something on my computer, Bittybartfast can watch a different show on the TV, and DH can be watching a third thing on the iPad, all at the same time. (There's a plan in place to start tiered service depending on how many devices you want to be able to use simultaneously - to cut down on people just sharing their Netflix passwords with friends - but the $8ish plan should be plenty for single-family use.)
- No good way to watch sports, other than listening in through internet radio on occasion. DH and I don't really follow any teams, so it's not a huge deal for us - we go to a friend's house when our college team is playing a major game and that's about it, really.
- Netflix doesn't have everything. There are some shows I vaguely want to watch that I haven't been able to. (On the plus side, they do have a smattering of British/Australian shows, so it's neat to see the "originals" of things that got chopped up to fit in American time slots.)
- Stupid little nitpick, but our Roku takes nearly a full minute to get from "turning on the TV" to actually being able to play a show. Didn't have this problem when we were streaming Netflix through the Wii, though, so it's probably just an issue with Roku.
In addition to Netflix, I watch a handful of other shows online (The Daily Show and Project Runway, for example) - again, not everything is available on the cable companies' sites, but a lot of them are.