Strictly on a UI/UX basis, it beats most other online dictionaries for not being annoying A.F.
I haven't done a close evaluation, but itcompares favourably generally.
I also use dict (Debian), which is mostly Foldoc and 1913 Webster. As well as several dead-tree dictionaaries & etymological dictionaries. Those stand up surprisingly poorly to online references in several cases, though the OED still proves useful.