Although the low score in IMDB, i didn't find it all that bad, to be honest, managing to keep my attention throughout the movie. It started out strong and i really enjoyed the intimate ambience, with few characters and detective-like feel to it. It's nowhere near the low score IMDB has, with some not-bad acting.
And it didn't finish strong; in fact it declined a bit by the end, but still, overall it's not a bad movie.
Is it worth the watch?
I'd say yes, for a very chill drama, albeit somewhat (not much, really) gruesome in nature - it is about Jack the Ripper after all.
As for the Horror tag, it's not so much horror as it's drama with a bit of lite gore.
It's an interesting movie, overall.