From what I've heard, the build they're playing at Eurogamer is the same as the MP Reveal and Gamescom so really they're playing on the same maps and restricted the perks and pointstreak selection.
They did show a new map "Stonehaven" but I don't think it's playable at the event.
I'm not sure what build they had at other expo's/reveals but the EGX one was very basic, 95% of it was still locked. Still a very fun game to play, I queued up 4 times and even managed a 1 of 500 free prestige edition.
Blitz which is similar to CTF is a great game mode to be an effective team in this you need a mix of play styles. You need rushers to get forward and get into the enemy portal and campers to protect you're own. When I played the first thing my team did was instantly run to the objective and after the first round we were losing by 4/5 "caps." I stayed back on the second round to protected our portal and we managed to turn it around and won by 1.
Domination is back to a single round with some very craftily placed B flags. On the map "White Out" it's in a tunnel with only 2 entrances, teams wont be able to just cap it and then sit back and defend for the rest of the game, they'll be forced to move around and get in there to defend the flag.
Killstreaks were really limited in the build you had a choice of 2 preset streaks and specialist wasn't available. I went for Satcom, Guard Dog and Juggernaut Manic. The juggernaut maniac is a fun streak to use my only complaint is that the knife should be on the trigger as opposed to B/R3 as it's your primary attack.
All in all well worth queuing for and I will be purchasing this game on release.