I've seen a lot of people talk about how quickly ODST outsold Killzone 2, however a quick search on this site will yield you many examples of how sales numbers do not directly reflect a game's quality. Mediocre games such as Wii Music (2.62 million) and Sonic and the Secret Rings (2.06 million) are just a couple of examples. Let's go in the other direction. An outstanding title such as Boom Blox hasn't even cracked a million. I used Wii games as examples because the Wii is full of mediocre titles with huge sales and outstanding titles with lousy sales. Don't judge a game based on sales numbers. ODST outsold Killzone 2 in 24 hrs.? So what! I'm not saying ODST is mediocre. I've read several positive reviews. I'm just saying play Killzone 2 before you judge.
Keep this in mind when reading what I type...
I've been gaming longer than many of you have been alive.