The Mysterious Affair at Styles

Okay. So the summary would be : someone kills someone else and Poirot finds out who, how and why.

The general opinion is that this isn't her best book, and I agree. An excess of red herrings and even more plot twists; more of a tiring and confusing narration than, a gripping one. Still it's good for a one time read.
Poirot notices people's characters, he finds out people's motives based on their characters. I find it annoying that it is not revealed to the readers, a description of their characters - not just plainly stating it, it could have been somehow made a part of a conversation.
Poirot just says “Haven't you noticed that so-and-so is a jealous person”
And Hastings says “oh really, I haven't noticed”.
Me neither, man.