The the main reason that statisticians love it is that the libraries useful to them are much better in R than elsewhere (though Python keeps encroaching in that turf, and "real developers" dislike Python a lot less than they do R).
The main reasons that developers hate it is that it is very unlike almost all other languages that they're used to. This is very valid since outside the narrow domain of statistics, there's probably nothing that R does better than other languages. So for a dev who occasionally dabbles with R by necessity, the otherness serves nothing but frustration.
Still, I wonder how much criticism there is against R as a programming language, that is not some variation on this works very differently from other languages. IMHO the sub-setting syntax, and countless x-apply variations are big warts. I'm not a big fan of Tidyverse, and even less of the schism between base- and Tidy-R. I read some seemingly fundamental criticism about R's deficient scoping rules, but I'm not nearly knowledgeable enough to judge their merits.
I guess it doesn't help that almost nobody learned R as their first computer (as opposed to statistics) language. Personally, I learned C, Matlab, Python/numpy, SQL, R in that order. R does seem to be quirkier than all the others, except maybe SQL. But I don't dislike working in R any more than working in any other language.