Absolutely gorgeous sound for Unobtanium guitar with Mithril strings, played by Cyborg from Alpha-Centauri. It has strings, it can be strummed, amplified but it does not sound like something you hear on stage, or near campfire.
Background for my opinion: I'm not a guitar player - only keys. My main music interests: electronic/edm/experimental/hybrid.
I tried to choose my first guitar VI to buy. Of course I wanted to find "most of the most" guitar: realistic, simple and powerful...and inexpensive :) I trialed couple of them: MusicLab, Amplesound...Absolute fantastic edge of technology, but all of them seemed to me like sample archive with several knobs - you can build a music with it, but it is not VI for playing with keys. Okay, okay - it is not rocket science - I got some results with keyboard, but just did not like workflow. Then, I tried AAS Strum GS-2: "Oh, that is not guitar...and this is guitar..and..woah! i'm playing guitar!". One, two... and I just got music sketch and experiment with a result. Tons of sound presets and built-in rhythmic patterns, but you can just strum with keyboard. Or tweak sound in a way you never thought it was tweakable. "Do I really need 100% authentic super guitar sound?"
Pros: Playable fantastic strumming engine, Playground for guitar sound experiments, Built in patterns and FX, Quite realistic as electric rhythm guitar (and fast).
Cons: Not so easy, fast and plausible as acoustic guitar or lead guitar, No scratches/squeaks/slaps.
Forget about cons if you can consider this VI not as guitar, but "guitar-like synth", or "sketching/experimental instrument"