I like that you can target your ads to specific audiences, it makes my life easier as an advertiser since i don't have to worry about all of those pesky cookie issues with google/facebook advertising! The ability for me as an adtech vendor to be able to deliver targeted audience data in real time is very helpful when trying to make decisions around buying inventory or bidding on campaigns.
There's not much at this point we dislike but they could improve their billing system so that payments are made faster than expected (2-3 weeks). Our business needs accurate reporting from our agency partners who aggregate traffic sources across many different channels which then feeds into our own account management platform - making sure we're delivering quality impressions via relevant media placements.