Performance pretty much there for me with xfire now.
On a single card I was getting 65fps maybe with grass density down one notch and hairworks off, 1440p that dropped to 50fps, 1800p that was down to sub 35fps. With xfire I get around 85/75/65 respectively. Cpu limited at 1080p in xfire, a little less so at 1440p, 1800p hitting both gpus at near enough 100% and great scaling from one to two cards.
Some flicker, need to play around with sweetfx aa settings, too late for that now.
Could the driver be better, sure, did a driver released way before the game work perfectly with a single card, yup. Is sli perfect on every launch, nope, is it always perfect within a week, nope, has xfire or sli at any time in the past decade been perfect for every game, nope, if you get more than one card and expect perfection you're asking to be disappointed.
There are times where both AMD and Nvidia haven't had a driver that works with a new game for a single card well. Some people like to overstate the problems and are completely delusional about previous drivers and the competitions drivers.
What I expect from AMD or Nvidia is 99% of games working day 1 in single card mode, what I HOPE is xfire working on most games from day 1, what I can live with and not care about is some games won't be great with two cards, that goes for Nvidia and AMD. There are numerous games where BOTH companies had huge problems giving good scaling or good support.
If this game sucked single card it would be a major problem but it doesn't.