CPU: Intel i7 4790 (Stock)
GPU: R9 295x2 (Stock)
RAM: Kingston HyperX Beast 16GB 2133CL12
Motherboard: MSI Z87M-Gaming
Storage: Samsung 840 EVO (OS)
Storage: WD 1TB 7200RPM (Game)
Display: Dell P2415Q 4K
VSync ON @ 60 FPS
Performance was actually fantastic. The game looks super slick, not quite as bright and shiny as Trine, but still pretty damn excellent. Despite the heavy focus on physics my system didn't take a remotely large hit to performance except when fire got involved. Even then, the game had a multi-GPU profile ready pre-launch so my 295x2 ate it for breakfast. Everything across the board was just so damn low on the usage, I found myself inspecting areas to figure out what was causing such a small footprint on my machine. I still have no idea, so I'm assuming the optimisation is just plain solid. I didn't discover any bugs through a single play through, however there were multiple occasions where quitting the game after an auto save would lose some of my progress - a nuisance, but easily overlooked. Overall a pleasant surprise.
For reference, you can see how your GPU will perform in comparison to ours with this set of charts.
NOTE: Precisely 50% GPU usage means only one GPU was put under load on the 295x2. This may indicate a lack of multi-GPU support.