Thriller was a series that it took me 35 years to watch. Everytime I sat down to try to watch it I suffered through the first five or six abysmal episodes which were blatant, and poor, Alfred Hitchcock Presents rip-offs. I never bothered watching the rest of the series, but then one day, by sheer luck, I tuned in to watch one of the later episodes and was "thrilled." "What happened?" I wondered. Well, to answer my own question ...
The show was so poor to start out of the gate that the studios were forced to either cancel the show or bring in a whole new producer. That rarely pays off, but once in a long while it does work. Thriller is one such show. The new producer changed the show from poor man's "thriller" to a great horror show. Thriller was one of those very few shows that improved as time went on rather than deteriorating.
Certainly the episodes were varied in quality. Even a few of the early episodes were decent and there were a few stinkers later on, but overall quality of the show was vastly improved as the series moved along. The best episodes were "The Incredible Doktor Markesan," "Pigeons From Hell," (don't let the name fool you) "The Hungry Glass," and "The Premature Burial" to name a few.
If you have never seen this series, but like horror, give this a try. If you liked Night Gallery, give this a try. If you like slasher horror, forget it.