It sounds okay, but never more than that - won't confuse it with an actual amp. You can achieve better clean, driven and lead sounds with other free amp VSTs: e.g. Amplitube Custom Shop, Cypress TT-15 and Crunck V2. The CPU load isn't great either, which means I wouldn't reach for it to do low-CPU live tracking before switching it out for something else (I prefer Cypress TT-15 or the Simulanalog Guitar Suite amps for that).
OK, it's free. Thanks BlueCat. While the clean sounds were 'nice', the overdrive sounds were akin to a chainsaw in a plastic box. They were very noisy and the hissing was unbearable. The mid range was boxy and artificial. It was almost as if no cabinet simulator was being used so that I added one which improved the sound quite a bit. Overall, I wasn't convinced. BlueCat make great stuff. But in this case, there are other freeware amp modules that actually do a better job.