It's not as bad as some others have written. People are overly harsh on horror more than any other genre. I love horror, love scary buildings, ghosts stories, people getting picked off one by one; truly not hard to please. With all that said this movie is very average. The acting was believable, the characters were interesting and the lore behind the manor was developed well.
However and maybe it was for budget reasons but this movie leans a bit too far into the drama and not enough into the horror. It was about 50 minutes in before we were done with the drama, which isn't too above average but it did feel dragged out. Maybe it just wasn't interesting enough to care. The movie wouldn't have changed if they cut out the divorce storyline.
That aside the spirits themselves were cool. Not a lot of graphics to be critical of, more make up work and audio. Also not a complaint.
Personally I enjoyed House on Haunted Hill, Gonjiam: Haunted Asylum. Hell House LLC, Interior 2014, the sequel The Devil's Toy Box 2017, or The House on Haunted Hill 2018, Eloise 2016, St. Osmund's 2013 to name a few more than Harland Manor. Though some of those are found footage films and I know many ppl take issue with those so be warned.