I didn't like it, but I loved it. Monster went from unpleasant to nearly unwatchable, but there was brilliance in every episode. It's not a date movie -- if your date liked it, might be a good time to disappear.
Stunning performances from so many actors -- Charlie Hunnam foremost, and Tom Hollander, Laurie Metcalf, Olivia Williams, Tyler Moore, Lesley Manville. Other supporting cast didn't miss a beat.
The writing and structure was just as strong. The loopy style requires a little work to grab but the narrative is consistent with the approach. Hunnam's performance helps glue it together for the viewer.
This is a master class in writing and performing contemporary horror. It is hard to watch. But in five or ten years it will achieve notoriety.