So what makes this worth getting excited over?
I know little of the series but from trailers it doesn't strike me as anything other than your typical FPS fair.
Blasphemy!
But to help you out here Joe, i'll sum things up:
The games in Battlefield Series are FPS of course, but they feature very, very large maps, generally vehicles (some maps more than others) including aircraft and BF1942 had larger ship such as destroyers and aircraft carriers.
The series features class based gameplay, but the number of classes has been reduced for BF1943.
The game isn't a standard deathmatch, rather it's called "Conquest Mode."
Basically there are a number of points on the map (control points/flags/objects/whatever you want to call them) that each side is trying to control. You capture a point similar to how you do in other games, TF2 for example.
Each team has a number of "tickets" which is basically just a number, usually around 200. The goal is too reduce your opponents tickets to zero, which you do by holding control points and getting kills.
Holding all the control points, and killing every member of the entire team instantly results in a win as well.
You really need to just play a game in the series ('42, 'Nam, of BF2) to get the gist of it. They're all really fun, but 1942 is the best.)
As the player you get points for kills and captures, so you can be the leader on your team (theoretically) by getting no kills.
Also, generally the player count is very high. I liked to play 32 player matches of BF1942, 'Nam, and BF2 but the option existed to have up to 64 players.
So solid teamwork is a must (especially when you're dealing with vehicles that require two person to work effectively) and it really feels like you're in a huge kickass battle, fighting over territory rather than just running around some dark hallways trying to kill some douchebag.
SO FUN.
One last note, the emphasis is on gameplay rather than realism, so the previous titles (particularly 1942) have been very arcade/action oriented - though they've got slightly more "realistic" as the series has progressed. But they're still about as realistic as Halo is, so it's all about the fun.
And as an added bonus, this game runs on the BF:Bad Company engine which features destructible terrain for all kinds of badass fun.
With me talking this game up so much I really hope it doesn't suck.