Let's start with punctuation, shall we?
The title is properly punctuated as I have it above -- "40-Year-Old" as a single compound word. The newspaper ads, however, have "40 Year-Old" and the opening titles of the movie itself have "40 Year Old." I suppose I should be grateful that they didn't find a way to stick an unneeded apostrophe somewhere in there...
As for the movie: Major disappointment.
Steve Carell has been very funny on The Daily Show and in supporting roles in Anchorman and Bruce Almighty. This is the first time he's been asked to carry a picture, and he's just not up to the task. He doesn't have the range to pull off this character, which is well outside his "pompous jerk" comfort range; as a lovably sweet loser, he's a total bore.
The movie's not very funny, either. The jokes are sophomoric gross-out comedy -- vomit and urine jokes are common -- and there's a lot of very nasty "you're so gay" banter among Carell's sidekicks that left a sour aftertaste. Lots of good actors -- Paul Rudd, Romany Malco, Jane Lynch, and Catherine Keener, playing a much sweeter character than her usual sharp-edged neurotics -- are wasted in this piece of garbage.