This past weekend I finished playing Halo: ODST. I found it to be harder than expected but quickly learned that several fights (especially those as the rookie) are best avoided. I enjoyed the title a great deal but was hoping for more teamwork throughout and not just lone-wolf style gameplay. I'd love to play a Halo game more along the lines of say a Republic Commando where your squadmates are at your side the majority of the game.
From there I started Halo: Reach. Both games I played on Normal. The game starts off with some firefights that are pretty brutal and I had to repeat them many times over. You have to use cover a great deal and not be afraid to fallback. Worth noting that the enemies CONSTANTLY move around non-stop in comparison to ODST. Drove me insane at points as they can get good shots off but its a good challenge. The game isn't repetitive when it comes to environments. It has in earlier titles but not here. Bungie did an incredible in making this game feel epic.
The best part about these games, particularly Reach, is by far the aerial and space combat. The controls where spot on and never did I feel like I was struggling to take enemies down or having trouble to maneuver. I'd love to see more games around space and aerial combat just like this. Bungie really blew me away here. Expecting to see more of this in Halo 4.