well, that depends...
As most have noted, components seem to sometimes provide a 'warmer' set of tones or colors. DVI should be able to provide more detail, especially edge sharpness.
One test we did at the store, when I worked for Ultimate Electronics, was to hook up a Samsung DVD (931) player with component and DVI cables to the same Samsung DLP television.
When playing a really good source DVD (we used Fifth Element, Superbit), you were able to see distinct differences in flesh tones and shading when switching between the two sources. The component looked good but the DVI almost (and I stress almost) looked as if it added a three dimensional q uality to faces.
YMMV, as a huge amount of your quality depends on source material, the player or box, cables, power supply and not least, the TV itself.
The only drawbacks I can see to DVI is, a reasonably good cable is more expensive, no A/V receivers switch DVI (yet) and most TVs only have one port (so an HD box and a DVI equipped DVD player are one too many).
But hey, other than that, try it out and see.