Im not sure that everyone hates it per say. I think it's partially b/c everyone that does like it doesn't feel the need to run out and tell the world while ppl hate it do. The negative will always ring louder than the positive. A lot of ppl still really like Halo, I dont like the multiplayer in H3 as much as H2 but the story was much better IMO. Though Halo 1 was the best in terms of story, but thats my opinion.
Everytime im on Halo an average of 250k to 450k players are on and thats not weekends. I believe COD has the most unique users per week (as in Major Nelson's updates) but I found an article not to long ago that said Halo3 had highest average of users on at any given time. I can't find the article atm but when I switch games, the numbers I see certainly show that.








