User Interface: It looks nice and simple, anything you need is there, like a real amp.
Sound: It sounds is perfect.....I mean you can get all the sounds you what from an amp, someone said is not enough metal, all metal guitar player knows you need stomp boxes to get that sound, so put some effects before it.
Features: The best feature to me is that you can switch the cabinet simulator off and use other impulses.......a big improovement should be to integrate an impulse loader right after the cabinet switch.
Documentation: You don't really need a Manual, maybe only to get the registration right.
Presets: Presets are not many but real amps doesn't have presets...:) Anyway from the few you can have a good starting point.
Customer Support: Didn't need any customer support....which is good to me.
Value for the money: To me is the best money I ever spent...and really not much anyway.
Stability: Never crash and very light on the CPU.