I had high hopes for the movie but I'm definitely disappointed. There is no keeping-you-on-your-toes mystery, it's more of a kids film tbh. However, if you are looking to pass time, it's worth watching once. Though I highly doubt I'd recommend it to any actual Sherlock's fans, be it Elementary or the RDJ movies. Also, it's definitely too long for a movie with no plot.
Your choice to watch is up to you at the end obviously.
I have also read a lot of other reviews and I can confidently say that the majority of the supporters and enthusiasts are hardcore fans of Millie BB and hence are biased. I'd recommend to not engage solely on those reviews.