I played the game through on Heroic yesterday in one 10 hour long 2 player co-op session.
There's some complaints, some broken promises and a several things that could have been improved, namely story distribution, but as a whole the game beats the second game out of the water: It doesn't feel like a pipe, good illusion there Bungie, there's a great amount of variety in combat and I also never felt like I was walking in a facade - the immersion is just grand. Furthermore, rather than the energy sword twitchfest that the 2nd game was, this one made you use strategy throughout and I constantly kept changing my equpment loadout. The new abilities, aka one time "spells" called "equipment", give yet more depth to the combat. On some levels, like Crow's Nest and Installation 00, bubble shields, regenerators and those godawful energy drainers made us switch from ranged to mid range to melee almost constantly. Add vehicles to that bunch, several which stand out immensely useful, and season the soup with the new enemy types like the constantly evolving new flood(Drone flood is gross and annoying), it is the best console fps ever. Perhaps one of the best fps ever.