I had a Multimix (note no "i" before multimix). Just doing a quick google, looks like the iMultimix is just the Multimix with an iPod input. If that's the case, I didn't really like mine. It was really noisy through the computer, and it introduced significant latency. It worked alright as just a mixer, but the effects, as you would expect, are junk, and the mic pres are obviously not the greatest.
I'm not sure what you want exactly, but if you just want an audio interface for recording on your computer, you can get much better ones for the same price (for my purposes, I really like the Presonus Firebox. No latency issues, no noise, lots of I/O for such a little box). If you want a mixer, you can find a better one for the same price used, I'm sure.
I'm not sure if any of this was helpful, but since there were no replies, I thought something would be better than nothing.