Putting aside 'that' single-player ending for a moment, it can't be denied that Halo 2 has provided a boost that Microsoft desperately craves, even if naysayers may argue that the series remains the XBox's only killer app. Still, if there's one thing dealing with the XBox has taught MS its that if you enjoy a temporary success then you shout it from the rooftops, as has been evidenced with their announcement of the Halo 2 stats.
91 million hours have been logged playing Halo 2 since the title's launch, far exceeding any other XBox Live game in the two years since the service has existed. 61 million logged sessions have also been recorded, with an average session lasting nearly 92 minutes.
Unfortunatly, no measurement was made of the number of curses, slurs, and times the term 'n00b' was used, if so we have little doubt the figure would have far exceeded both logged hours and logged sessions, and sales figures for the matter.