From the PlanetXbox360.com feature article:
"Halo 4 is inexorably marching towards its November release date, much to the anticipation of longtime and rookie fans alike. While there is a lot to be excited about, as a fan of the series since prior to attending the launch party for Halo: Combat Evolved before the arrival of the original Xbox in 2001, it seems worth stepping back a few feet and looking at what exactly we can expect with what will be the eighth entry into the franchise."
Read the books and you will have an idea.
a majority of those are not reasons to hesitate in my opinion.
Wait a minute they are.