I'm just going to claim that anybody who doesn't play guitar won't notice the difference between a sim and a real amp sound unless you showed them an A/B comparison.
With that in mind, do you like it as a guitar player? Does it make the sound sound more like you want it to? I don't know the program but I'm highly doubtful that it will sound like a real 4x12 half or full stack cranked to high gain. It can still sound good though.