This drum instrument is great and fills a much needed gap. It sounds great, and the developer has shown a lot of dedication to improving this plugin very quickly and has taken feedback very well. So much attention to detail and workflow has gone into this to making it easier and more musical. In my opinion Speedrum has already surpassed NI Battery in functionality and workflow.
I'm using it in Logic Pro X and I find it more useful than drum machine designer, although there aren't really any kits out there for it. Hopefully that will change with time.