I have used Adstream for my publishing/editing company and I loved how it was able to reach different types of clients in different areas of life. To me, that is crucial because I am able to reach a broader audience which in turn helps me package my product differently for different clients.
Smaato is very well suited for user acquisition and retargeting companies. Their overlap in terms of audiences and publishers with other exchanges is very limited, which makes it a great alternative when you need to scale a campaign and want to maintain your frequency cap. They work very well in branding campaigns as well as performance campaigns.
I personally am not involved in the decision to renew the product, but I had only positive experiences with the product and thus would recommend its use and renewal.
Smaato has a UI where you can control your line items on the traffic you want to receive. That is a key unique selling point that other SSPs don't offer. Most of the items that you will need like reporting can be done on a self serve manner and that is a big plus, specifically for changes that need to happen really fast and you don't need to deal with account managers that may take some time to answer emails.
Smaato's account management team is very professional. They are quite fast in terms of customer support, which is very helpful. One item that stands out is that they are willing to understand what you need for each campaign and what is the best way to move forward. They don't just jump quickly into trying to upsell more of Smaato's products (audiences, data) like other SSPs do.
I love Adstream because it does a great job at streamlining its ads to different components and different industry providers unlike Apple iAds and Google AdMob. It also is very helpful for a new business like myself to reach different audiences and hopefully generate some revenue from these types of diversified ads.