Yawn.
The sequel wasn't released in the holidays and the pc version probably stole some sales because people probably thought the sequel would have the technical issues of the original and they thought the pc release wouldn't have as many graphical glitches. Not to mention the pc release was day and date this time.
Couple that with how highly connected it is to the original and you've got the bad legs accounted for as new users would only get the full experience if they played the first. Not to mention sequels in general are more frontloaded because the fanbase from the first will buy it more quickly.
However I think overall it will outsell the original it just wont grow as much as some people expected it too.







