If you aren't going nuts with the amount of controls, the new mini-pac looks like a nice all-in-one solution with regular encoder, and trackball. If you want a lot of controls, it won't be enough.
I like the iPac for a few reasons
Andy Warne (of ultimarc) frequents this board and is very helpful. There is wide spread support and interest in the iPac (mac, pc, etc) and Andy seems to be very aggressive at releaseing new and excellent products where there is a need. The shift key function is nice, and the software is very easy to use to program the iPac.
I don't know that it is better than other models, but for the average person, I think it is unquestionably an excellent purchase. Somebody has a big comparison of all the encoders around here... don't know the link.. it might help if someone posted that again.
The one drawback that the iPac has is that it doesn't support key-macros. I don't need them, but I could see them coming in handy for others.