Here are the reasons that people don't like Big O:
1. It confused them one time and so they hate it. Same thing goes for Wolf's Rain. They saw it one time and it confused them. It's the second worst anime...of all-time! Right behind Big O! Ever!...in the history of anime...!
2. It has a giant robot in it.
3. Inuyasha rocks!
4. They've never seen it, but...well, it's not Inuyasha!
5. The storline is so gray! (minus the 'r')
6. The opening theme segment is bad...as far as the rest of the show goes...uh, I don't know, I didn't really watch more than a few seconds of it...uh, I like colors...they're pretty.
Of course, there's a few others, but they get repetitive. When it comes to Big O, just like any other show on AS, most people either exaggerate one way or the other and make themselves look like fools. Mr. T pities you all.