The art was about on par with the main series, with the usual very pretty backgrounds and variably okay-looking main characters (which is funny when episode 2 has a tropey bishounen/ikemen moment meant to wow us with how "gorgeous" the Moriarty + co fam are and it's just... really unimpressive because the characters just aren't drawn well or by and large interesting to look at). The music is by and large the same as the series, with nothing to stand out.
Of the two, the first episode is definitely the more enjoyable, and worth checking out, particularly if you want more Sherlock & William, or want to see an anime set in Bath, England. The second is nice if you really wanted to see the tea party manga chapter animated. Neither story is particularly good, but the second episode is infinitely worse, and at least the first is kind of cutely shippy. This isn't to be mean to fluff (I like a good fluff story) but the second episode seems to focus more on the fact that the audience should recognize and like the tropes being used already, so they'll like the episode, rather than writing a good story with the tropes or using the cast well. It's particularly unfortunate because a lot of the tropes rely on attractive character designs, which this series almost uniformly fails at producing. But if you find most of the cast attractive, maybe that'll be your favorite episode. It's otherwise overly corny and boring in a way that I found unenjoyable.
