To LOVE-Ru Darkness is another harem/ecchi anime that is of course, not for everyone. It's a sequel to the previous Motto To Love-Ru and To Love-Ru.
The plot of this sequel is very expected, like most other anime. The author(s) did not focus on trying to create an extraordinary story, but instead focus more on the art.
This is why people mainly watch To Love-Ru Darkness and its prequels, the art and of course, the fan services. As I said in the "Story" section, the author(s) focused on this category. The art was perceived very well and extremely detailed. I love it.
The sound effects in this anime is pretty well-done. Sometimes there are unnecessary effects, however there are times where the sound effects actually make you enjoy the anime more.
This category goes with "Art", the artist(s) did a nice job with the character design, he successfully think in the boots of the viewers "What kind of characters would I like to see in an ecchi/harem anime?". Well done.
Yes, I enjoy it a lot. The fan services brought together by the author(s) was at a conceivable level. Nothing too annoying. The humor was extremely good and well-perceived.
I would recommend this anime to any ecchi/harem viewer. Although keep it in mind that this anime contains a lot of adult contents and this anime is not for everyone.