IS FUCKING RIDICULOUS. I’m playing in Co-op and my partner’s main role is to be a res point as I die over and over killing things. It is TOUGH.
Edit: so I’m a few levels into it and really , its interesting to see how its really the first couple levels that really kick your ass and minus maybe 1-2 situations after, its fairly easy.
With the three grenade skulls on, it’s not terribly tough with a partner. There’s just those few parts of the first level where the Jackals rip you apart with snipers and carbines.
Gosh Darn Suicide Al Quaida Grunts come and blow me up.
QFFT
Maybe it’s because of Halo 2’s Legendary (which truly was ridiculous; first level ugh), but I didn’t find 3’s to be all that tough. The fact that the game doesn’t revert to the last checkpoint when a partner dies makes it quite easier.
There is a skull that enables that function, 984.
So I’ve heard. So I’ve heard. That should up the difficulty, yes. For the most part, I still didn’t find Brutes as hard as Elites.
Agreed. Halo 3’s legendary is way easy compared to Halo 2. When one person died you both had to start over 
and I never actually beat the first level in halo 2 on legendary but we’re half way through Halo 3 on legendary in co op.
Brutes take more damage methinks and wear helmets. Thats really all that makes them difficult.
The key to beating Halo 2’s first level on legendary is to use the Plasma Pistol/Battle Rifle combo in the various points that the Elites and Grunts pop out of the spaceship holes.
Actually, now that I think about it I think we did finally beat the first level. Took like a month though lol. But those were definitly the hardest parts (where they pour onto the ship from those holes in the walls and seem to never, ever stop).