The UI is very clear and easy to use.The alerts are great! We have multiple services that we run at our organization and it was difficult keeping track of them all in one place before kiali came along.Kali has helped us see what's happening across our infrastructure and keep everything updated! There aren't any downsides that i can think of right now.
But if there were, they probably wouldn't be too big a deal either. If you're looking for something simple but powerful this product will do just fine. We've been able to quickly identify issues within our systems without having to manually check logs ourselves or call support.