I'm sure someone's gonna come in and type a whole essay about their opinion so I'm gonna make my answer real simple. No sprint
This question is way too broad to generate any meaningful discussion. Just Google both games and check out the Halo wiki entries.
Things halo 4 has that i dont like but halo 3 did not: sprint boltshot the ability to spawn with boltshot, plasma pistol, and plasma grenades not enough community
Halo 4 r cawl of dooty and halo 3 r cool with equipmant and geud bungie fourge suppuort stuffs Halo 3 maps our better two Heh