CE's melee is fine, you just don't get a forgiving lunge and have to actually aim, kinda like the precision guns compared to later Halo's as well. Claw or change your settings if you are having trouble aiming your melees.Yep.
Heresy: I'm not a fan of either Assault on the Control Room or Two Betrayals. I think it's the constant up-and-down, one bridge to the other side, go around this room monotony that starts setting in.
The only level I actually have a hard time figuring my way around though is 343 Guilty Spark. Whether or not I end up wasting time heading back up to the broken lift, or I end up in the same rooms, seems entirely arbitrary. That one's going to suck trying to speedrun, I'm probably just going to watch someone's run and then just pause constantly to parrot it.
For me CE's melee system doesn't really age that well; it always feels a little cheap when I feel like I've sidestepped an Elite and he still thwacks me, and that makes it a bit harder for me to judge when to time melees. And on Legendary, infection forms turn into a legitimate threat; you're better off making sure you killed them with a pepper of AR fire or a shotgun blast rather than missing the melee and having them deplete your shields.
I usually just round up spores and whack them with Melee as well, they don't do a whole lot of damage, and are pretty easy to manage. I only shoot them if I am in a bad way with no shields, or trying to preserve my Overshield, otherwise I just kite em and melee.