I wouldn't say it's the greatest out out of the three Hercule renditions but I found it overall quite enjoyable. The director made a lot of nods to classic Venice films which I thought were cheeky. In fact, much of the movie played out like a classic film and I was mesmerized by this.
Without spoiling the plot, the clues were laid out evenly enough to identify the mystery while adding many red herrings to distract. It's probably one of the more simpler mysteries out of the ones that have gone to movie, so keep that in mind.
I noticed some reviews state that the movie was too dark, I didn't notice that. As I think back on it, it's definitely darker than the other Hercule Poirot movies as the other two were high color, this one went darker to fit the theme. There's still high color in this movie, but only on the people, and not nearly as much as the other two movies. Everything in the movie was easy to see.