I don't know why I like it so much, I guess it is the simplicity of just having to setup the Mbox 1, ibook and a set of headphones. Then either a mic or the bass in direct. I have also gotten it to work with MIDI by just plugging my M-Audio USB keyboard straight into the other USB slot on the ibook.
I recorded a singer/guitarist a few weeks ago with it and it worked fine with him. I just made sure to mute the track I was recording to so that he didn't hear any latency delay, used the mix knob to get the right blend of the incoming source to the tracks for him and set it to mono so that he heard everything in both ears. Worked fine. I did run a patch cord out from the headphone output into a 3rd party headphone amp that can power up to 4 sets of headphones so that we both could monitor.
I started to lug the Digi 002 rack/ibook rig to where we were recording, but got overwhelmed by the prospect of having to disconnect the snake, monitors and everything else and just took the lazy way out with the Mbox. I have a session on Sunday where I will need to use the Digi 002 Rack to record drums and keyboard at the same time, but that will be the 4th time I have ever had to use it instead of the Mbox and I have had both of them over a year. I will sell the Digi 002 Rack long before I think about getting rid of the Mbox. Different tools for different folks I guess.....
bilco