David: I'm not sure what to say, because I'm not sure what your expectations for display quality are. Most modern laptops and tablets have excellent screens and display quality, but of course, that's a relative thing. If you're trying to compare your ST5111 to, say, a high-quality desk top monitor, then there's a chance that you'll be disappointed. But if you are comparing it to another laptop or tablet, the ST5111 should be quite comparable. For what it's worth, I have owned two Fujitsu tablets, and both featured excellent screen quality and brightness.
However, You may have some kind of problem. I suggest that you contact Fujitsu tech support and discuss this with them; they may be able to suggest some simple adjustments or tests that may help to identify problems, such as not having the most appropriate display driver, etc.