I currently have amplitube running on my iPad but was disappointed that I couldnt play along w/ my iTunes library. After seeing that this app is compatible w/ the iRig accessory (along w/ instant access to my tunes), I decided to go ahead and download.
First off, the app works -- nothing great, it just works. Immediately, I noticed you have to crank the apps volume to get any sound from your guitar / bass (also must have iPhone volume blasted) and this results in a noisy hiss every time a note is played or held. It goes away when not playing.
Another issue is the artwork w/ in the music player tab -- the forward, play, previous buttons should grow in height and not be so compressed, something about this tab UI seems like a cheesy rip off of the iPod app.
Like other users have mentioned, please add better guitar tones or a way to dial in a better tone. When playing along to my tunes, it just sounded a bit like butt. Please update soon -- Im sure this app has promise!
Im running an iPhone 4 w/ the latest software.