Campaing Mode
I dont mind the Halo Universe. in my opinion its an exceedingly magnificent story (It does have crappy parts too though) Although it can get quite boring after playing the same missions again and again.
Online Play/Xbox Live
The main thing that i personally hate about Halo is playing online. The amount of times i have joined a game on Xbox Live and been killed by some jackass 11yr old, who has spent the last 3 years of his life playing Halo, with a sniper rifle hiding in the trees because he knows every stupid place capable of being exploited.
Microphone speak
And then when you get to the whole speaking ability on it. The amount of people who just either sit there and scream at you for doing something helpful, while he/she sits there in a little Hidey-Hole hidden away. Then we move onto the squeaky voiced 8yr olds. They squeal at you as if you can understand them, and as if they make any sense. Eventually you get the Music-Players who just play absolutely stupid music on full volume blasted over the Mic. And when you get to the piss-head players who kill you despite the fact that you are on the same team, they do it stuff-loads of times, you get fed up with it, so you grab an Energy Sword and slice him through the stomach, Suddenly to find yourself on your Main-Menu because you were kicked from the game for committing Friendly Fire.
Real Life
And then the Halo universe gets into real life too. The amount of people at school who hear that i have an Xbox 360 and then scream at me in person to get Xbox Live, or to go and play with them. I went on a party with one of them before. he joined me to a game with 14 other people whom i all knew from school (all the sort of people who have no lives at all) and they start screaming through their mics and running about in a blind fury throwing Grenades every where and shooting randomly. And i get back to school the next day and half of them come up to me in person and tell me im a "noob" at Halo because i didnt kill anyone, because they just threw Grenades everywhere and killed most everyone (I left after 2 mins) And to be honest, the noobs in BlockLand have nothing on the people from Halo.
And that is what i hate about Halo