All the people who like it (The good or at least decent players) will say its balanced, others will not.

The game DOES NOT have balanced weapons thats not how halo works. The guy who said he uses the machine gun is smart because its the only sure kill weapon that you could actually call Overpowers (Same with the WH turret). Halo balances through the players ability to dodge everything thrown at them (hence the reason the instant hit weapons are so great) sure the needler beats almost everything but a good player (Or one with experience with the needler) will void it and kill you with there instant hit weapon.

If your going to call something OP lets talk about the Sniper Rifle, its literally an all purpose weapon. Want to argue and say "But it shoots slow" why do you think Counter Strike is such a unoobfriendly game? Oh hey thats right people got good with the sniper (Notice the "Got good").

Melee weapons can also be bad but a player should no the way around this one. Just to top this off though you could argue that if someone got as good with the needler they'd be as good as a sniper, not true because as i said above (I know people would just remove this fact if not repeated) ITS A 100% SKILL BASED DODGEABLE WEAPON NO MATTER HOW GOOD THE USER IS.

In the end whats this mean. Halo is by no means balanced as far as weapons are concered, its balanced through that fact that every player can learn to dodge your shots unless using the instant hits (Mainly the human guns) then its like CoD on EasyCore.