It comes down to hoping all your shots you fired were registering (netcode was one issue, but the game also had bad hit detection, see the Sniper and its bloodshots galore). Let's get away from
hoping our shots hit because of a spread or, in the DMR's case, bloom was set.
If anything it's ten times worse. I hop over maybe once a week to play some custom games and going from Halo 4 to Halo 3 sucks so bad. The netcode is pure shit. It ruins all the fun for me. But, if you can look past that, the maps and gametypes are still top notch. AR starts are still terrible. Vehicle gameplay is still good though.
dat VIP on Snowbound
But honestly, outside CTF/Heretic, CTF/Pit and 1-flag/High Ground, there isn't a lot for me. They killed objectives for me as much as 343 did in Halo 4. There's VIP which is straight awful, large dose of Territories which is okay but nothing great, Assault that got its balls chopped off, and CTF that has no difference in return time between large and small maps.
When it becomes free I'll play it again for the first time since Reach came out. I played Reach the other day but with the playlist management destroying it last August (or whenever it was), there's little to play in there too.