First of all - the computer. It is amazingly fast. I went for an SSD to boot Windows off it and it just runs like a dream. The games run really smooth and you can hardly hear the computer - noise levels were really important to me. It comes really well packaged with all manuals/CD's etc.. The Windows Experience Index is an average of 7.5 (out of max 7.9) for those interested.
Second - the service. In one word, excellent. I've contacted them before ordering and I received a extremely detailed reply within 2 hours. I was updated at every stage (e.g. parts ordering/building/delivery etc) and the PC was on my doorstep at 8 am on the scheduled day. I even wanted to add something AFTER ordering and my request has been handled promptly and professionally. I am extremely satisfied with both the PC and the level of service and will certainly be back when I upgrade. Many thanks guys !