Which basically said that the force has a relation to little organelles common in cells in the Star Wars universe. A minor point that I remembered, thought was cool and went on enjoying the film.Star Wars wrote:"Midi-chlorians are a microscopic life form that resides within all living cells. Without the midi-chlorians, life could not exist, and we would have no knowledge of the Force. They continually speak to us, telling us the will of the Force. When you learn to quiet your mind, you'll hear them speaking to you."
Then some time around 2006 or so I heard some people bring up what was a minor bit of trivia as a criticism of the movie. Then I saw it again and again as a frequent criticism of the film. I understood how people would not like Anakin Skywalker's potrayal or found Jar Jar Bink's annoying and agreed with them. Other criticisms I felt were dogshit (specifically the moanings of the mob of marching morons that is the anti-CGI crowd) but at least they were criticizing something which was commonly used throughout the series (to it's benefit, by I digress). But Midi-Chlorians? Really.
The criticism that I get for this is that it takes some of the mystique away from The Force by making it into another scientific phenomenon. Frankly I don't buy it. First of all Midi-Chlorians are not The Force. They are only said to be a link between the Force and "Higher Life Forms". It does not contradict what is said about the force in the original trilogy, that it is born of all life. The line about Midi-Chlorians only state that there is certain intermediaries involved in some way. It does not answer all questions about the force by any means. This is on top of the fact that I think that I have no problems with Unweaving Rainbows and it's only logical that Force Users in a scientific society would try to understand an objectively verifiable phenomenon even if their insights are at best incomplete. Besides Darth Plagueis did good things with Midi-Chlorians in the lore in the EU.
But leaving aside all of that there is the fact that Midi-Chlorians are a blink and you'd miss it thing in the actual films. They come up three times in the Prequel Trilogy, one of which is in one of the best scenes in Revenge of the Sith. But finally the existence of Midi-Chlorians does not lesson the emotions of the characters, dull their motivations, make the actions less spectacular or their world less vibrant. At the very worst midi-chlorians is a sandgrain sized chip off one of the Solid Granite Columns on which the franchise rests.
So in short the whole "Midi-Chlorians Ruined Star Wars" is one which does not hold up.