I built this computer specifically for GW2, and normal computer usage as a birthday present to my husband. This build runs GW2 on Ultra very smoothly. We have yet to test the actual FPS in high traffic areas like WvW but so far he seems to be getting 60fps wherever he's playing.
The build went extremely smoothly. We took our time and put everything together, being careful to double check the manuals if we weren't sure of something. Cable management was a breeze, and everything looks really clean. Windows install went perfectly, drivers install went perfectly.
The couple problems we did have was GW2 didn't like the Render Sampling set to Supersample. The game got a black screen within seconds of playing. We changed that back to Native, and there were no problems after that. The other was that the sound stuck when he quit the game, so there was a repeating buzzing of whatever millisecond of sound was last playing. This issue seemed to heal on its own, and I'm not sure what the issue was at all. It may have been our monitor, but nothing changed and the computer was restarted a couple times during that issue and it still did it. Since it stopped doing it on its own, I'm not really sure what it was.
He's been monitoring the temperatures, and even during a stress test everything remained very low. The highest temperature was the R9 280x at 51 °C with the room temperature being about 70 °F. The CPU was staying at 45 °C, and the motherboard at 29 °C. Load times are looking good as well. From powering it on to fully loaded it takes 20-25 seconds. From password entry to fully loaded it takes 5-10 seconds.
We're very happy with this build so far, and I think we will continue to be very happy with it. For the price, I don't think you could go wrong with it if you're looking for a GW2 rig. It is a bit overkill, but a little overkill is better than underkill when you were hoping to max it out. :)