The best thing about visx is its ability to connect with various networks, both traditional as well as new ones which are still being created by other ad tech companies; it helps us get more impressions at lesser costs than other platforms would have charged for similar campaigns or placements. I don't think there's anything bad i can say against this product so far! We use Vis x mainly because of their API integration but also due to our close relationship within VSP partners where they do all the heavy lifting of getting clients into ads exchanges like Adbrite and Double Click etc..