I've had mine since 2008 and about two weeks ago noticed a white dot just above-right of center. Googled a bit and learned about the DMD chip failure issue. By the time I called Samsung support last Thursday I had three white dots. Over the weekend two more appeared. Samsung authorized a replacement for the DMD chip with me paying only for labor costs (~$200). Actually it's more complicated than that one rep said it was authorized but forgot to give me a service transaction number, and when I called back to get a service transaction number, the next (VERY rude) rep said my TV was not covered. I called back today and escalated just to figure out which was the case and they verified that it's covered for a one-time replacement. The part is ordered and should be installed by the authorized service center soon.
I've also had two of my three HDMI inputs go out. Only HDMI3 works now. The other two show "Mode Not Supported". I'm using HDMI switching on my receiver so it's not a big thing, but I am concerned that the third will go out and I'll either have to pay for more repairs or break down and get another screen.
It's been a good TV and I'm pleased that Samsung is actually covering a significant portion of the repair on a six year old screen, but I am disappointed with what now seems to be three failed components.