It takes only a few minutes. First you need to remove the trim around the radio by sticking your fingers in the power outlets and pulling. It's just snapped in place and that is the best spot to grip. The bottom edge frees up first so you and usually wedge a finger under that and pop the rest out. Once it loose, unhook the wiring harness for the power outlets, etc. There are screws on each side of the headunit, remove them and pull it out.
2007 H3 - Red 5sp w/ Sunroof, Toyo 35's, PIAAs in the driving lights and Sirius on the HU