The default style for the Android TabHost works fine for straight Android systems. However, on HTC Sense, they use dark text on a dark background, which is unreadable.
After some research I think the best option would be to use ActionBar's tabbed interface since it looks much more easier to style. The ActionBarSherlock provides compatibility layer for ActionBar for devices starting from Android 1.6. Here you can look at examples on what you can get using the library.