It's really fast, easy to use and it works well for our needs. I can see all my metrics in one place and it has a nice dashboard which makes managing my tests easier than other tools we previously used. There are some limits regarding performance (for example memory) but they're working hard at solving this issue. The free version is good enough for most cases and we were able to identify issues without spending money on this tool. We've been using Locker.io since last year and have seen an improvement compared to previous solutions.