It's possible to read this as an attempt to control the game's hype before release, and it's possible to read this as a roundabout statement of overall quality. Either way, it's an odd statement coming from Blizzard's public relations team, since very few developers have historically told their fans to be a little less excited for release. Of course, with that having been said, it's unlikely that the level of excitement will go down at all. (Bashiok's full quote is just past the cut.)
"On a more serious note, I too worry that we won't be able to meet the expectations people have built up for themselves. Part of my job is managing people's expectations, so... eh... stop it. Stop thinking about how awesome this game could be. Just imagine it's a new M. Night Shyamalan movie. Sure Sixth Sense was amazing and Unbreakable had it's moments, but this right here is the sequel to The Village ... or The Happening ... or Signs ... or any of the movies besides the two I first mentioned. So just like, lower those expectations, but still definitely buy the game please, and everything will be just fine. K?"