I've made a number of fretboards from Ipe. I suppose a lot of people will call it a bland wood but I kind of like the greenish/brown homogeneous color. It certainly fits the bill for hardness and polish-ability. One thing though...Ipe can have very thin stress cracks that are impossible to see until it's polished. I found out the hard way on a neck. The answer for me is to polish the fretboard surface prior to gluing it to the neck.
You have to cut it with carbide blades and bits...but that doesn't bother me any.
Other than that...I'll certainly use it when that color fits into a scheme.