So far this is great. Finished the second flashback mission before having to stop to get work done. Haven't tried firefight yet.
Open world/hub stuff is really great, and so far, has the best visuals and music. Playing as an a weaker ODST guy is really noticeable in a good way; I'm playing on heroic and it reminds me of Halo 1. I do wish they balanced it out a bit more by making you faster or giving a run/sprint/haul-ass button, but it's no big deal. The new weapons kinda suck, though. Pistol isn't anywhere near the beastliness of the Halo 1 pistol, and it's just one of the crud pistols from 2/3 with shitty scope. The SMG is also kinda crap and I thought it would be better at long range since it has a scope. And someone on GAF said the POV changed, and I haven't played Halo 3 in over a year to tell, but the controls and all feel a lot better.
Just about the visuals and music, it seems all over the place. Human characters still look bad and makes the already dull dialogue even worse. The hub sections look pretty damn good; the lighting and general atmosphere is perfect. Then there is that second flashback mission that looks like butt; I don't remember Halo 3 ever looking that bad. Same goes for music. The hub section has really nice music that reminds me of Blade Runner and Mass Effect, but then that second flashback had some terrible music throughout. The first flashback wasn't too bad.
and I only heard two audio logs so far, kinda dull stuff, but I just played Arkham Asylum and you can't top jokes about severing a baby's limbs.