Aaron is right, as usual. I've had Opus from 2001, 2002, 2003 ... all within the last 18 months. All were excellent. In fact, I plan to smoke one tomorrow from 2000/2001 (either an RdC or a DC ... can't decide .. but it's my day off with no kids, so it's "big cigar time").
Interestingly, I still find them to be pretty strong after all that time. Not as strong as they were, but still punchy and leaving the mouth a bit numb. Either med-full or even full-strength still, depending on vitola I suppose. The last aged Opus I had was only like 2006, and it was stronger than the older ones, but not quite as refined (different vitola, though).
I have an "A" coffin from 2007 (the year my son was born), and I probably will save it until his 18th birthday. I expect it will still be good.
If you like cinnamon raisin bread ... smoke a well-aged Opus
I know sorta someone who got a full box of OR Opus X (from Carlito I believe), he says they are still out of this world.