Jim, it really depends on what you're building and what you have in mind for a finish.
A few years back, a Facebook forum for sci-fi builders were very strong advocates for using a combination of Tamiya's Pearl White and Pearl Clear to give a "regulation" Federation style paint job to match the Enterprise from the motion picture. I wound up picking up those products, as well as Tamiya's pure white spray cans to test out things before I threw it at the starship.
Some people like it, but I guess that I'm not one of them. The clear has a bit of pearlesence to it, but the 'glimmer' is very subdued over light greys (Tamiya spray primer) and white, but almost disappears completely over Tamiya's Pearl White. To me, it just didn't look right for the Enterprise, so I passed the pearl stuff before trying them out over different colors.
The situation may be much different for a car modeler, but I can't really say. I can only state that it didn't quite match what I had in mind, despite what I had been reading at the time.
My advice is to pick up a can just to test it. Try it over different colors, maybe try building a little depth to the finish with a coat of Tamiya gloss, it's up to you. After all, you're the only one who knows precisely what you expect to see in the finished model. Photos (when available) really don't show much of what is by nature an already subtle effect. You really have to see it for yourself and make your own judgement.