Carbide tools are essentially just scrapers that stay sharper for longer than HSS tools.
For myself, I find they have a use in certain applications - I find that turning ebonite for instance, is much easier with TCT than with HSS, because ebonite blunts HSS in nano-seconds, and I usually put the final cut on an acrylic with a TCT, used as a shear scraper as Alan mentioned above. I could use HSS for both of those however, but the "stays sharp for longer" part is quite handy, especially with ebonite.
I have to say though, that if you know how to use traditional gouges, and you know how to sharpen them, unless you need a TCT for a specific task, you will be a much more versatile turner if you stick with the traditional tools. I own use both, and in my opinion there is no advantage in TCT unless you need a sharp tool right at that moment.
The advise I would normally give is similar to the previous two answers. If you've never turned and you want to make something today, get a carbide - the learning curve is minimal compared to traditional tools. However, if you know how to turn, and you're comfortable with traditional tools, stick with them.
(Carbide tools do go blunt by the way, and you do have to sharpen them)