I remember how huge a lot of people seemed to think Nemesis was going to be when it was on its way, all the hype around it. And then it was finally released, and it was a disaster, a total damp squib ruined by poor decisions on the part of the makers, and corner-cutting. Very, VERY underwhelming, and a big blow to everyone who'd looked forward to it. In all honesty, this is kind of how I feel about DW's fiftieth anniversary special right now; Moffat and the BBC are hyping it up enormously, but there are also some indications that it won't do the last fifty years any real justice.