It has been around on desktop systems for some time, but db Audioware's Flying Haggis is now available for iOS.
"A bunch of well thought-out presets give you access to a range of amp and effects tones"
What you get is a colourful but simple interface that offers a single amp with drive, distort and compress knobs and three-band EQ.
This feeds a choice of six cabinets with various mic'ing options and reverb. You also get six stompboxes - noise gate, auto wah, phaser, tremolo, echo and chorus - and a bunch of well thought-out presets give you access to a range of amp and effects tones.