I just wrapped up the 2nd season of the original Star Trek today. I got the Blu-ray's when they got cheap and have been watching a disc or so a week. I'm watching the show with the original effects option. I had watched the whole series a while back and the DVDs I watched had new effects inserted. It was fun to see the old effects and I enjoyed the shows all over again. I'll have to switch to the new effects the next time I see them.
I wrote long posts about the season back in 2012. You can read those by clicking the Star Trek Season 2 link in the CATEGORIES column.