Shoushimin is pretty much in the same vein as Hyouka, so if you liked that series, you'll probably like this. Shoushimin is subtle in how it handles its characters and scenarios. Rather than having a major overarching driving plot that's obvious from the beginning, it takes an approach where each seemingly-disconnected mystery pushes things forward a little bit, telling us more about the characters, their circumstances, backstory, and where they're going from here. Hyouka does this too. What Shoushimin offers on the surface even if you're not really invested yet, is great sound, breathtaking cinematic visuals, and a relaxing pace that invites the viewer to be present in the moment and take it all in. Already, though, it's clear that there's more beneath the surface than what first appears, especially with regards to the main characters.
The biggest downside for me is that the main cast is much smaller, focusing almost entirely on the two main characters with very little development for the others so far, though that may change with time. The writing can also come off as a bit convoluted and heavy-handed sometimes, but in general I think it's alright.
So honestly, it makes no sense to me that this is getting so much hate. It's slow, yes, and I'd expect that the average anime viewer probably wouldn't be into this, it's just inherently a style that's not for everyone. But Hyouka was slow too, and took a good few episodes to feel like it was going anywhere meaningful, and Hyouka fans seem to be acting like this is somehow different. I'll join the other Shoushimin believers in saying give it time, currently we're only 5 episodes in and IMO it took around that long for Hyouka to click too. And I wouldn't be concerned about the fact that it's only 10 episodes, it adapts two novels so the pace is basically the same as Hyouka, and if it catches on, I imagine there's a chance the rest will be adapted in the future.