Well I haven't used it personally, but man I can't see ever becoming used to such a separation between the screens.I've been running a 3 monitor Eyefinity setup for nearly to 3 weeks now, and the bezel are not an issue. Your brain just adjust to it. Even my miss-matched monitor size setup (25.5" + 27" + 25.5") isn't an issue.
Btw, Eyefinity is gaming bliss. The added peripheral vision adds so much immersion to gaming. I'm surprised there's so little talk about it here with this supposed hardcore 3D audience.
One major issue though that I saw from the demos was the aspect ratio - you would have a normal AR image in the main screen, but then the two at the left/right would be significantly warped. Do the games you're playing on it actually adjust the AR or offer to do so manually (something I wish so many games did and did not tie it to resolution, kudos to the Riddick developers for example).