I used a converted cabinet so there was already black t-molding all around. I wanted something different, so I pulled it out, and already had the slot for it to fit in.
I already had the cabinet laying on its side, so I just started at the middle of the bottom edge, pressing in as I went, following the edge of the cabinet. When I would get to a corner I would notch the tongue of the tmoldingif it was an "inside" corner, or cut a series of V shapes if it was an "outside" corner(liek the bottom front corner). Also when I got to a corner I ran down the edge I had just pressed in with a rubber hammer and it snapped in very nicely. Just continue all the way around till you get back to the bottom, cut it to fit and press/hammer it in. Its very secure and I didnt need to use any glue or filling to tighten it up
Why? Well, it is an authentic look. It's nicer to bump or rub against than a wood corner. It comes in many colors, so if you have a mainly black, or any monotone color cab you can add something that contrasts for a nice look. I went with red t-molding on a mostly black cabinet, and am using red sticks and buttons. It looks sharp.
As far as being a PITA, I had a good time with it since I already had the slot cut. I can see it being trouble if you are building from scratch and not experienced with a router.