The letter to the investors went into much more detail, and that's what caused the recent share plunge. A couple things stuck out - churn rate is up, they lost more customers than expected, they expect to continue losing customers into the next quarter, and they spent more than double the amount on streaming content.
From Q3'09 - Q2'11 Netflix added between 500k - 3M customers a quarter, so losing 800k customers in a quarter is a huge change. Especially when costs for new content are climbing.
The $9.99/$15.98 plan is for streaming with 1 DVD at a time. Other plans allowed for more DVD's at a time and blu-ray. The letter mentioned that they had customers who had, but did not use, streaming. These customers dropped down to the cheaper DVD only plan after the price increase.
This is anecdotal, but the Netflix customers I know, including myself, all changed to cheaper plans. In short, they're hurting.