It has gotten decent reviews.
http://www.gamerankings.com/htmlpages2/932615.asp

78% Average atm with the score being brought down by the usual no innovation stuff. If you like shooters and want a large online battlefield it seems like a nice game for it.

Official Xbox Magazine 4/1/2008 9 out of 10 90.0%
Xbox Addict 2/24/2008 8.6 out of 10 86.0%
Games Master UK 3/1/2008 85 out of 100 85.0%
Gaming Nexus 2/25/2008 8.4 out of 10 84.0%
Worth Playing 2/25/2008 8.2 out of 10 82.0%
TeamXbox 2/25/2008 8.1 out of 10 81.0%
GamePro 2/25/2008 4 out of 5 80.0%
GameSpy 2/25/2008 4 out of 5 80.0%
VideoGamer 2/22/2008 8 out of 10 80.0%
TotalVideoGames 2/22/2008 8 out of 10 80.0%
Jive Magazine 2/20/2008 4 out of 5 80.0%
IGN 2/25/2008 7.6 out of 10 76.0%
Game Informer 4/1/2008 7.25 out of 10 72.5%
Xbox World 360 Magazine UK 2/27/2008 72 out of 100 72.0%
Edge Magazine UK 3/1/2008 7 out of 10 70.0%
gamesTM 3/1/2008 7 out of 10 70.0%
Official Xbox Magazine UK 3/1/2008 7 out of 10 70.0%

 anything on the framerates and lag?

 Huhn, isn't this game the one where... Frontlines matter though?  That seemed like innovation to me.

@ant We'll probably have to wait until the servers are bustling to find out, before Warhawks was released it had zero lag, then after a massive hit people were experiencing a little, it wasn't till shortly after they got they're severs overhauled :P So I'd say wait until the game is released to find out what we'll be looking at :)

the maps are too big for 32 players... personal experience with the demo.

It's basically a vehicle combat game with the option to go on foot.