I don't like it as much as dplyr and I stand behind that. It's too "clever", especially with respect to joins.

Everything is fine "once you understand how to use it", even assembly code, but it's not equally expressive or intuitive. So I don't value data.table speed that much, it's my thinking and typing speed that's usually the limiting factor. I would always recommend dplyr over anything else for someone learning how to use tables.

I also can't help but point out that data.table has the worst first FAQ answer I've ever seen in software documentation: https://cran.r-project.org/web/packages/data.table/vignettes.... Just astonishingly bad. I could write an essay about the unique and diverse ways in which this thing is both incredibly poorly organized and deeply user-hostile.

But if you truly have a need for speed on large datasets, it may be for you.