I went to the M12 release event at my usual place, as the London pre-release I usually go to wasn't running, it was the first time I got to play with the new cards.
In general, I think the set is quite fun. I didn't do very well on the day (a mixture of my opponents being very good, but mainly me playing badly).
Opening the sealed pool (the first event we did), my first pack had a Gideon in it, so I thought I would be in White. I also got some Dragons, and generally good cards among most colours (apart from Blue).
I ended up making two decks - one Green/White (a backup deck) and one Black/Red.
In the B/R deck, notable cards included Vengeful PharaohFlameblast DragonVolcanic DragonSengir VampireChandra's OutrageIncinerateVampire OutcastsGorehorn MinotaursDuskhunter BatDrifting ShadeTormented SoulFiery HellhoundFling
Vengeful PharaohIncinerate, and I could attack to win the next turn
Chandra's Outrage, Vampire Outcasts, Blood Ogre, 2 Gorehorn Minotaurs, Bloodrage Vampire. I also had Goblin Fireslinger and Goblin Arsonist.
I thought I had an aggressive deck (my mana curve topped out at 5 with Crumbling Colossus), but the first match I played my opponents deck was more aggressive (2/2 bears for 1, small white creatures), and I made a bad Mulligan decision again at least once (Mountains and Black cards again), and couldn't do much about a Serra Angel.
My second opponent had a W/B deck as well (but they splashed black), and pretty much the same thing happened (my deck wasn't fast enough, my opponents creatures were faster and more powerful). They did play the creature that has a Fact or Fiction effect when it came into play, in one pile I put a black card (they had no swamps) and a non-swamp, and in the other pile I put a swamp, other land and the hexproof boots, which I thought was the most optimal (for me anyway) split.