I've had two Halfords bikes, The Gryphon which was nicked and the Valour which I still have. It's worth noting that both of my bikes were first generation of their series, meaning they were very well spec'ed. For instance, my Valour which is essentially the same bike came with a full Sora/Tiagra groupset, Tektro brakes and some basic wheels but they were a brand I'd heard off. The saddle was a selle italia too. It cost me £240 brand new and not in a sale. Brilliant value and top bike, it's still going strong albeit with better brakes, new wheels and saddle but the rest is still stock and got plenty of life. The frame has been abused like no ones business but it's still great 5 years on. Not the comfyest, nor the fastest but it's decent enough. Sadly it seems once it got a decent rep they removed all the more expensive bits and replaced it with cheapo stuff. I probably wouldn't buy the Virtuoso.
EDIT: It's worth noting that the Valour is actually the next model up from the Virtuoso.