Netflix requires an existing Netflix account. This starts at $10.99/month for an account w/ unlimited Blu-ray + streaming. For this you get 1 DVD or Blu-ray mailed out to you at any given time; when you return it they mail the next one on your list. You can pay more to get more discs at a time, like I pay $16.99 for 2 at a time.
Now this streaming thing is they have a bunch of mostly older movies & TV shows, some 12k titles or so, that you can watch over the internet on a PC, through newer BD players like Samsung/LG, and other devices like TivoHD/Xbox & some new TV sets. These you browse on the web and add to a list, then you can stream these directly to your player over the internet, watch immediately without having to wait for discs to be mailed. The selection leaves something to be desired (only about 1/7 of the movies I want to see are available this way), and the quality varies considerably between titles (only a few hundred are available in HD, & their encodes are not as good as Blu-ray; SD is variable, usually somewhat worse than DVD). Also there is no 5.1 audio on these yet. But it is a free add-on to the main mail subscription, and a good way to catch up on older titles while waiting for your next BD to arrive. I wouldn't want to watch an action/sci-fi/comic movie on it, due to the lack of 5.1. Nor would I watch a new release movie that they didn't have an HD encode of, I'd rather see the Blu-ray. But there are still plenty of titles to see, and it rates to improve in the future (more HD encodes, adding 5.1 eventually).
Wireless only helps if your Blu-ray is not located close to a wired ethernet connection, and you have a wireless router to connect to instead.
Also for good quality streaming you need reasonably fast internet, preferrably 4+, 5+ Mbps otherwise quality will drop particularly for the HD titles.