Playing at games workshop Bromley today. I played two games from the new battle missions book. I chose 'War of Attrition' and my opponent (Death Jester) chose 'Pre Emptive Strike'. I lost both games. The first game was a close run thing right up until the end two turns. Turn one I smashed all of the Eldar tanks, wiped out the rangers, shattered the bike squadrion and wrecked half the walkers.  At the close of turn 3 every vehicle on the table was a smouldering wreck.  The Bailed out Wriath guard wrecked both of the Vendettas with gunfire and assaults. At the end of the game it was grenadiers vs wraithguard, which is not much of a contest.  My troops ended up cycling onto the board a couple of times each, guaranteeing the Eldar victory.  Without the Bane wolves, getting rid of the Wriath guard was nigh on impossible.
The second game never came together for me. My HQ started the game standing out in the open and was  anihilated with extreme predjudice in the first turn. The banewolves didn't turn up on the board until turn five and even then arrived on the wrong flank. 
My opponent very skillfully arrived at every fire-fight on the board with maximum concentration of his army, usually facing desultory fire from one or two of my units. Both fun games though and I probably learned slot more from the second game than the first.