Opinions of Vitus frames vary wildy. Some claim they ride like wet noodles while others cite Sean Kelly's numerous victories on Vitus frames as an indication of their race worthiness. Undoubtedly, they were very light frames for their era. The standard diameter, metric aluminum tubes also provide a very resilient frame with a comfortable ride, though at the expense of stiffness. Whether you will find it flexy or not is matter of personal preference and riding style. There have been some instance of the tubes separating from the lugs.
Fortunately this is a very small frame and the tighter triangle helps stiffen the frame. Also, small riders are generally lightweight and not quite as strong, which minimizes the flex.
Regarding value, it seems that these have lately been selling for $150-$200 US, in good condition. Not having colored anodizing would knock about $25 off the price.