First off, I'm going to say I hate Reach. Bungie seemed to scrap this game together because they knew they were done with Halo. These changes made Reach IMO the worst Halo game ever...even worse than ODST, which I didn't think was possible. Adding armor abilities was a good idea but it was a huge fail for the most part. It was almost like they tried to piece together different aspects of other major games like the sprint for Cod and the evade from Gears in order to please a greater audience. But instead, they forgot what made Halo, Halo. With such a loyal and loving fan base that is the Halo universe, they should have stuck with what we liked. If it's not broke, don't fix it, right?
Now for the controversial subject...bloom. I personally hate bloom. I left Reach for many reasons but the main reason was bloom. Having to time shots is not Halo IMO. In Halo 2, it was about aiming for the head every shot. Shooting as quickly as possible to take down an opponent. And it was fun. I think fast enough in the game between callouts, moving, and watching weapon respawn times to worry about how big my reticle is. I'm a good shot and when I die because someone is spamming and the auto-aim takes over, it makes me mad. I have recently started playing Reach again but only ZB playlists. It still isn't great because of jetpacks and armor lock, but its better.
As a long time Halo fan, the best Halo game was Halo 2. It put the video game industry on the map. I feel 343 needs to revert back to the style of play in Halo 2. Bring back classic maps like Lockout, Midship, Coagulation/Blood Gulch, and Warlock/Wizard, instead of relying on players to forge them. Take weapons away like the needle rifle and add the old Carbine, the 4 shot BR, and if they feel generous, the BXR and doubleshot. I know the latter two were glitches but they actually became part of the game and were allowed on the MLG Pro Circuit at the time. It was so gratifying to be low on shields and kill someone with a simple BXR.
Maybe I'm crazy but after two crappy releases like ODST and Reach, I find myself looking back at the good times I had at LAN parties playing Halo:CE and Halo 2 wishing to do it again. So bottom line, 343, look at how Halo 2 made it the pinnacle of Bungie's existence. The maps, the PURE gameplay with no armor abilities or bloom, and please, if possible, the BXR and doubleshot.