I agree with many improvements mentioned in the inital post. I will explain my feelings/reasons for this.
Spartan Ops seems redundant. The maps are straight out of the campagin (understand) and the exact same area is used repeatedly. After playing for a bit, it seems like the entire point is to just shoot people. There is a great story developing with the episodes that has very little to do with them game play. You have very limited objective other than killing, such as, press a button or acknowledge an object.
Multiplayer: The biggest improvement I would like to see if more weapons in the load outs. I was susprised to see you can't have a shotgun. This has always been a part of the Halo fun. It might be because the one in CE was a little over powered and acted like a rifle with spread, but that is besides the point. The power and range have been reduced. If you choose to have a shotgun it could be useful on smaller map types. However you are still vulnerable do to the limited range. A shotgun and pistol with scope has always been my favorite combo. You have a distance weapon with lower power and a close range weapon that can do some damage. I would also like to see more close quater maps and hope there will be some in the map packs. I have an urge to play some longest.
Overall Multiplayer: I'm tired of playing the same map repeatedly if I'm playing the same game type. I know this is based on voting and will improved with more maps, but why even list the map you just played as an option for the vote? People will vote for the one they know, like, or just dominated on in the previous game.
Another idea I have is to make a poll for players to vote for thei favorite map from each version or at least CE, 2, and 3. Then we can have retro maps based on popular vote. I loved the original Blood Gultch and enjoy the remakes that are in almost every game after but why is that always the one that makes the cut?