Me, i find the Jackal Snipers to be the least of my worries in Halo 2 Legendary... But then i've played the game so many times (on Legendary) i remember their locations and deal with them first.
Still don't do well against Brute packs, that final section in Uprising is hellish, two Wraiths and respawning Brute packs until you get a checkpoint...
Still, it is still a wonder Bungie thought they'd be fine as they are. In Halo 3, Jackal Snipers at least miss on the first shot nearly always. But i guess they simply ran out of time from really testing them, or figured they're just fine on lower difficulties. I mean, Halo 2 Legendary co-op resets to checkpoint if either player dies so it is deliberately made to be really difficult.
And speaking of difficulties...
Halo CE Legendary is mostly tedious. The way the Covie weapons work, they're not a big threat for most part but damn the enemies have a lot of health. Just takes time to bring them down. EDIT Flood with Rocket Launchers are an exception though. And for some reason Flood levels tend to have poor checkpoints or their triggers are glitchy.
Halo 3's Legendary is too easy to be honest. Mechanically it is fine though Flood Stalkers are slightly too tough to be fun to deal with, especially since higher-powered weaponry is scarce on Flood levels (Brute Shot is excellent against them but not always available).
ODST is too easy as well, beyond Coastal Highway which suffers from Buck's inability to shoot properly and at right targets. Ironically this is due to ODSTs increased health compared to the Master Chief
Reach isn't that difficult either but the flawed game mechanics cause massive issues and slow down playing considerably. Whoever thought it would be a good idea for AI to be able to head-shot the player.... i hate you.
Halo 4 is easy on Legendary for most part, the only real difficulties are sections with Banshees (when they don't get stuck) because the AI is ridiculously accurate with them even from long distances. The third mission is especially bad about this because the Banshee sections are really small areas as well.
No comment on Halo 5, not sure i'll even bother playing it on Legendary. Just not good or fun enough to play in the first place.