WUT
Grenade Launcher will be just fine. It'll still kill in 1 shot if you hit them right, and it will still strip shields. This weapon won't be effected.
Shotgun campers may be a bit less effective, but that weapon is close quarters. If its close enough to kill, it still will and should.
Sword. This will be effected in a good way. Sprint-sworders will be taken out easier now since you aren't having to counter bloom while they are running at you with a death stick. You could apply this to the Hammer as well.
Needler will still be effective at its range. It may be easier now to stop a Needler dude, which is a good thing. Its not a power weapon so its should be able to be stopped easier than it is now. Right now you are dead if you can't get behind cover as soon as you hear it. Zero bloom will also help fight dudes spaceshippin' up in the sky with the pink mist, which is also pretty unfair as it is right now IMO.
Plasma Pistol - How would this be changed? Its ROF is still high and can pop shields quite quickly. Its overcharge will still be plenty effective at stripping shields too. I can't think of anyway at all this would change.
Pistol will still have a higher ROF than the DMR so if you can aim and are up close, the Pistol should still win. It will be tough still though with a smaller clip than the DMR.
AR is already pretty powerful IMO. It has incredi-range, magnetism, etc. IMO no bloom would bring the DMR back to balance with it and even the playing field. Sure it'll get more difficult for AR users but as it is now its too easy.
Plasma Repeater, Plasma Rifle, Spiker - These weapons suck and are useless. Anyone that is effective with them now is mostly likely playing at a lower level and should still be able to use them just fine. I say this because anyone decent at this game should have no problem taking out these 3 weapons. The Repeater was awesome in the beta, but now its just a wussy gun.
Man, typing this out and thinking about it makes me excited and I want zero bloom even more now. It seems that the sandbox will be much more balanced than it is now. What else ya got?