My impressions so far:
1. The ghost is way too overpowered, it can kill you in an instant; and when you stick it, it often times does not kill the ghost.
2. Oddball in epitath needs to go. Hiding behind the portals with the skull is unstoppable, that includes shotguns. At least the game ends quickly usually under 3 minutes.
3. Snowbound is painful when you match against campers with shotty / maulers. I have played in matches where the game goes the distance and ends with scores such as 28:26
4. I love the spatan laser the way the charging time was implemented was genious.
5. Not to hot on the brute weapons maulers, spikers, and the hammer seems a bit redundant. Of said weapons I only use the Maulers.
6. Needlers are relevent again, deadly in confined areas, like the rocket spawn in the pit.
7. New form of grieving? I was playing with a de-leveler he would follow me around the map and shoot me until my shields were down so I would die easily against the enemy, and he then let them kill him afterwards without shooting.
8. I'm a bit disapointed in the maps, it just doesn't have the awesome maps Halo 2 had. Such as Lockout, Ivory Tower, Ascention, midship, and colossus.
9. Individual reloading for dual wielding is awesome, although I rarely ever dual wield.
The game is awesome, for the most part the mechanics have been improved from Halo 2 in about every way.
