A colleague of mine at work who has a heavily modded impreza Sti Spec C had his car Plati-dipped in Matt Black over Christmas.
In terms of the quality of the job - it looks alright.
However there's no getting away from the fact that it looks a but crap. It cheapens the car somehow, and a few non-car people have mentioned how @*!# it looks and asked why the hell he would do that.
Before i saw his car, i would have considered it on one of my cars. After i've seen it, im pretty sure i now wouldnt.