I bought the Tascam iU2 to use with Garageband on iPad.
On receipt, it was clear that this was not a 'new' unit as the box and internal packaging had been opened / damaged, it looked like a returned item.
I had selected this as I wanted a compact recording interface with Guitar, Mic and Line inputs with no reliance on external power, the Tascam ticked the boxes against limited competition.
In use, the unit plugs into the iPad using an 'Apple-type' 12 pin connector, this does not click in like the Apple, but pushes in and this can be problematical for a reliable connection. I had several test runs before I was able to get an acceptable signal, the first takes were clicky and distorted and it seemed the solution was to wiggle the 12-pin connector, unsatisfactory!
In use, the Guitar input was fine and I took a line out from the Band's PA with good results, listening back through both Line out and Headphones from the iU2. The two identical Mic inputs can use phantom power which is provided by plugging the USB lead from the iU2 into your Apply power plug, I liked this because it also charges the iPad. Trying both Mic inputs with and without Phantom power gave different results, the L input was fine but the R had no signal, don't know why as I tried everything.
In summary, this is a good idea but Tascam should have gone for the iPad market instead of including Windows capability as the Pad will only record one thing at a time. It could then have been a better design with more of the rear buttons on the side/front as turning over to switch connections or phantom power on/off will disturb the fragile 12-pin link. Also, the build quality could be better as alongside an Apple product, this feels flimsy and overpriced.