Wtf, 3-5 hours of gameplay?
Regardless, I'm gonna admit that I will still buy it. Why? Because I beat all the Halos and it would be a disgrace (and dishonor) not to continue the fight. But that's the only reason why. I don't wanna be one of those douches who will later say "hey u know what i beat all Halos except ODST coz it was too short and way too expensive."
Consider ODST a filler to keep your nuts warm until REACH arrives