The game runs well in Eyefinity, with a few quirks. The UI is absolute positioned and does not make use of any multi-monitor API to identify the center screen like many other modern games do.
In MMOs it is generally not an issue since you can just manually move all the UI elements to the center screen, but they are static in ESO, so some vital elements, like the group window, is on the far left screen, making it impossible to see other than with your blurry peripheral vision.
During the beta weekend, the Fullscreen alternative in the game options did not work as intended, which means that Crossfire solutions like mine cannot make use of the power of any additional video card. Luckily the game is not so heavy to run, so it is still playable at massive resolution with a single card, but it would have been nice to be able to keep a steady 60 FPS all the time, which would have been possible if both cards worked as they should.
SLI users can still use some of the power of their extra card even if not running in fullscreen, but it is at a reduced capacity.
The tilted effect you can see on the sides is an effect of the field of view. It looks a bit weird now, on a flat surface, but as you play in Eyefinity, the monitors slightly surround you and in the corner of your eye, the trees will be straighter (although not perfectly straight since your monitors are not smoothly bent like a globe).