I really enjoy watching Agatha Christie's Poirot. Have you seen it?
I haven't seen it actually!  But, I have read Agatha Christie's Poriot's Early Cases.  It's a series of short stories she wrote back in the 70's.
Yes, the television series is based on her Poriot short stories; each episode was adapted from one of the stories.
Really?  Well I guess i learned something new today.  I still remember buying the book with pocket change I had saved up. It costs 2.25 euros. 
What was your favourite part about the stories?
My favorite part was how Poirot reminds me a bit like Sherlock Holmes.  It was so interesting how he solved cases and acted as the main protagonist throughout the whole series. 
Yes; I agree that Poirot was an excellent protagonist. He encompassed the idea of the 'British Detective', in both the short stories and in the television series.
I really admire Christie for being able to make such an intriguing character.  I learned just now that she wrote 66 detective novels.  That is extraordinary. I struggle to write even one diary entry haha.