We use A/B split testing and heat maps to determine how useful Yo is and it is definitely grabbing visitor attention and getting people to click on the products. This is great for exposing products that aren't as popular and getting extra engagement on our site.
We've used several other similar apps but the price seemed quite high for a simple yet highly valuable functionality. As store owners, we tend to add several apps to our arsenal and this adds up the monthly cost.
The price is fantastic with Yo and all the necessary features are available. I especially like the simple design of the notifications and the ability to set the placement of it in different places so it doesn't overlap with other apps that display on our site.
The app pays for itself many times over and has proven to increase our conversion rates and time spent on the site. You're losing money if you don't use Yo.