Having read a lot of Agatha Christie books, I feel like when I do read them I am quite at home. I enjoy her style and she often reuses phrases and idioms throughout her books. 
The Mysterious Affair at Styles was her first Hercule Poirot book, and who doesn't like Poirot? I can't say this was the best book by her that I've ever read, but it is fun to see the detective in his debut. I like that this book had some courtroom scenes, I love courtroom dramas. As this is an earlier book for Christie, I felt that the suspects were a little less fleshed out than I remember suspects being in future books. This made it a little harder to keep up with everybody, but as usual there was a good twist ending.
If you are a Christie fan and want a fast read, pick this up for sure.