I, for one, think the Silverlight player is phenomenal.
I have limited Internet options-- even though I'm living urban I am not close enough to a CO to get decent DSL speeds (the max Qwest offers is 1.5Mbps). Cable is not an option because my complex has a contract with the television provider who wired the buildings at construction, which is good for those who watch any TV since you get 50+ channels of cable television for free, but bad for Internet options.
Long story short, my Internet connection has a very high bit error rate percentage because I am getting my DSL over Qwest's line but from an ISP (AT&T via Covad) willing to boost the artificial limit of 1.5Mbps Qwest imposes to 3Mbps, at the expense of a quality signal. This results in being able to truly realize the faster speeds, but also in having a very burst-y connection.
I find the new Silverlight player to be far superior with its buffering saving the day, allowing me to watch Netflix streaming at maximum quality. The fact that the Silverlight player adjusts quality on the fly is outstanding as well-- when I first start streaming content it may look like shit at first but after a short time it is crystal clear, it realizing my connection can support the data load with a little buffering.
By contrast, with the old player, even before I had this error-ridden Internet connection, I would find myself initiating an instant streaming session only to find the stupid player would decide my connection was slow and give me piss poor video quality. I would have to click the "Back to Browsing" button and reinitiate the streaming several times sometimes in order for it to give it to me in high quality.
The new player also provides a great new feature when seeking through the content, where it will scroll past freezeframes of the content as you scroll forward or backward, which is perfect for skipping the intros for TV shows, for example.
I only wish it would "back buffer" a little because currently when I rewind a little bit, rather than replaying it from memory it rebuffers altogether, as if I hadn't just watched those few seconds prior.