I played some last few nights, thankfully it still has Halo written all over it, so anyone who was expecting a totally different kind of game than Halo 2 would be disappointed, I was for sure not one of them
First Impressions The biggest WOW factor for me was the sounds, from the grenade cracking to the distant gunfire, it was really amazing to hear. Graphics are definitely sweet but not Gears quality, but still beautiful enough to stop and take a look at that thing. MC's looks are bit changed and the jumps seems a little higher to me.
Weapons The game is full of weapons now, there are so many of them it becomes a bit hard to choose from, the AR is the perfect starting weapon, you dont go looking for another one and can jump into the fight with just that and do decent damage. Still controlling the power weapons is important to winning the game. Needler is no more dual wieldable but much more powerful, about 10-12 hits and you're done. plasma charge doesnt track that much anymore, so its harder to pull off the noob combo. Auto-aim has been significantly reduced for BR and Sniper, makes it hard to do swipe headshots.
Equipment and Support Weapons Its hard to predict the impact of these, I havent played with them much to make an assessment, Shield Drain or whatever thats called, made some fun moments.
Vehicles I tried Mongoose quite thoroughly, its a lot of fun and you can pretty much take it anywhere, it goes into pipes to stairs to rooms to anywhere. I wasn't able to jack it though? Ghost seems a little slower to me.
Maps Between SnowBound and HighGround, i really liked HighGround, the map is perfect for any kind of game as long as the party size is smaller than 10. Valhalla is a BloodGulch/Cogulation derivative and as beautiful as Yosemite, its best suited for big teams, but 4v4 objective games will still work.
User Interface Options and a lot of them, from match making to voice output to Spartan armor, but the defaults kick in so that you dont get lost if you dont want to. Controller settings will take some time to get used to. i keep on dropping my bubble shield to board mongoose.