They have a great number of classic amps (Twin Reverb, Bassman, Dual Rectifier, JCM800, AC30, etc) and they're pretty accurate in matching/emulating the tone of the actual amp. The presets that are included are definitely diverse in genre (everything from metal to shoegaze), so there's a good selection. It has a preinstalled bank of preset rigs and tones that can be pretty decent, but I like starting from scratch since I think it sounds better that way.
GR5 Pro is the same way- if you have a good ear for getting the right guitar tone then it's perfect but if you don't know what you're doing then it will sound awful. I like to compare it to Photoshop- Photoshop is an amazing program where if you know what you're doing you can do some really cool stuff, but if you have no idea how to use it then it's going to look awful. It's pretty simple to use, as long as you know what each of the units is. I love this program since I love trying to match a guitar sound exactly as I hear it in a song, so all the gear in here has made it really easy to do. There's so much stuff in here- a ton of amp heads and a ton of cabinets, plus loads of classic effects pedals (Boss DS-1, Tube Screamer, Big Muff, Boss CE-1, etc).
