Im not a great guitar player, but even I notice the latency with this app. If you want to work on your chops, just play your guitar, forget about little gimmicks like this.
Further, Ive owen a lot of the amps this thing claims to emulate. Its not very close.
My suggestion: get a SansAmp. If you must play through your iPhone, not the worst choice you could make.
jeffshattuck about AmpliTube Fender™