The ability for us to track our ads across multiple platforms, which is essential when looking at ROI! It's also easy enough that any member in my team can use it without needing training or support from an outside vendor. Their customer service has been amazing as well - they're always quick with responses via email / phone calls. I wish there were more options available within their reporting section (e.g., custom reports). We have used them since 2015 so we are familiar with all aspects of how effective this tool really is.