I've had this PC for 2 months now. Not a single problem. I'd like to give some of my average FPS to let you know what its like.
League of Legends 1080p Very High Settings 60FPS
Rust 1080p Fantastic settings 21FPS / Fastest settings 55FPS
Payday 2 1080p High settings 25 FPS
WoW 1080p High settings 40FPS
I have recently bought an upgraded Graphics card, the best value for performance at the minute (Nvidia GTX 750ti) and this computer is perfect for upgrades like this. There is so much room inside the case and space for 2 extra GPU's. The PSU (Power supply unit) is 550w which is more than enough for this GPU which only uses around 50w and the CPU is quite powerful at 3.6ghz.
The only thing you'll need to do is upgrade the graphics card but honestly if you dont mind playing on medium settings you don't need to.
The only bad things is there is no HDMI ports but if you get an additional graphics card you will get a hdmi port with that. Also it doesnt have built in wifi so you will need to buy a wireless dongle with the purchase which only cost about £10 or less (unless you want to plug an ethernet cable in).
I highly recommend this product. One of my friends got this same pc after seeing the performance for the price.