I've been playing this every day now since I got access and I got some information for new players or those interested in the game:
There are now four gametypes: Team Deathmatch, Capture the Flag, Rabbit, and Arena.
TDM is like all other TDM games; each team starts at 100 points or lives. Every time you die, your team loses a point. First team down to 0 loses. Caveat: After the first player dies, they drop a flag. Whichever team holds the flag, every enemy player loses 2 points, instead of 1. So in this game, you'll be seeing one player with a flag, with a dozen opposing players chasing him throughout the map trying to get it. Meanwhile, the flag carrier's teammates are all doing their best to defend him and kill those chasers.
Capture the Flag is "capped out" at 3 captures. Each team starts with their own bases, complete with base turrets, vehicle station (you can "buy" land and air vehicles), and inventory stations (change out armor, reload ammo, etc.) There are now 4 different maps (maybe 5, I can't remember) to play on, all with their own unique design (snow, molten, beach, mountainous)
Rabbit is a gametype where there is one flag, and your goal is to hold onto it as long as possible. Very similar to TDM, except instead of having teammates help defend you when you got the flag, everyone is gunning to kill you instead.
Latest new gametype is arena. Just like World of Warcraft, you're placed on a presized map to fight it out against the other team. Best 2 out of 3 wins the match; it uses the same concept as TDM, where your team has a set number of lives before the round is over. Largest matches are 5v5, but it can be 4v3, 2v3 as players join or drop out of the match (disconnect).