It started with all these "other" devices that have Netflix now. So they started offering streaming only accounts for ~$5/month. $8/month is pretty reasonable to me. Their streaming was extremly limited previously, but with the new deals there's like 200% more content available than just 6 months ago. While everything I would like to watch isn't available via streaming, there's enough that is and that catalog will only grow. Those deals that allow them to stream a ton more content are no doubt the reason why the pricing is goning up.
What you will NOT see are major new release films up for streaming right away unless they add another level for that. New films just don't show up right away.
It is also not always HD, when it is, it is 1080i, and unless you have a PS3 it is stereo only for audio. Even on the PS3 it is 5.1 only and only a limited number of titles.