We have had a Roku 2 for about two years, with Hulu+. Unfortunately the free Hulu only works on the computer, not on the Roku. Back in August we decided to give Amazon Prime a try, and honestly regret it. Not worth $100 a year. Once that runs out, we'll probably try Netflix. For our one hour of TV-watching time per night, it keeps us well-supplied.
There are some interesting channels on the Roku for free; some History, NatGeo and PBS shows have unlocked episodes. Plus there are a lot of interesting documentaries available on YouTube, which now has a stable channel of its own. If you like obscure movies that you've never heard of before, there are a lot of channels out there. A lot of church channels, cooking channels, some kids channels.
The only issue we have is CBS. They held out on Hulu because they wanted more money, so now they have their own mobile app with a monthly access fee. Right now we're watching the back episodes from the website on my computer and hoping we can get caught up on NCIS before they start removing episodes. I'll have to check into Playon and ustvnow.com.
We also picked up a Homeworx digital tuner for about $45 that allows us to record OTA TV on a separate external hard drive. It works pretty well, although we have to watch our weekly recording schedule if any of our shows get shifted out of their normal time slot. I just need to get a bigger hard drive, so we can start recording all the CBS stuff. We also installed an external antenna on the old dish mount on our garage.
+1 for Pandora; spend a little time setting up your favorite "stations" and liking/disliking a few songs to tweak it.