My pc is not a powerhouse: intel dualcore 2.4 GHz, 4 GB of ram, 2008 with a Line 6 UX1 audio interface and it turns nickel, no problems, no crashes, bugs or latency (if installed at the ASIO driver of course!).
For months I use it and I'm in love! Of course it has its faults, but all software, amp simulators and effects have! I tested the Overloud TH-1 and 2 and I much prefer the guitar 4 pro rig. Ditto for The Amplitube! I find distos huge reverbs, delays and other nickel. I record with no problem and I admit that made me like it. Live on the other hand is more complicated. It should return the computer and pedal, but frankly it's not rocket science. I have trouble understanding why Cerain opinions are so severe compared to that commodity prices are for, is among the best in its class. After if you want to sound as pro ultra buy a closet racks and amps at 2000 euros each!