The Matrix was excellent because it came out of nowhere. The story was engaging and the action sequences were superb. The sequels tried way too hard to do everything "bigger" than the first, and they ended up a mess. When they tried to expand the story of the matrix to include the architect and the keymaster and the gatekeeper and the millionaire and his wife (yes, I deliberately referenced both Ghostbusters and Gilligan's Island in describing the plot of Matrix: Reloaded, which should give you an idea of how retarded that movie really was), things went beyond "convoluted" into "complete nonsense." Couple that with action sequences that go on for so long that they get boring or feel more like a tech demo than a well-choreographed action sequence (Neo fights off hundreds of Agent Smiths because we can do that with CGI!), Jesus God... it's just bad film-making. And they try to write really powerful, moving speeches, but they aren't very good writers, and their actors aren't equipped to deliver the emotional punch they're trying for, so you have Keanu and Carrie Ann Moss just chewing the scenery with the most overwrought bullshit, which becomes downright unpleasant to watch.
I'm not saying that there aren't good moments to be had in the sequels. But compared to the first one they were such a letdown that it actually cheapens the effectiveness of the first movie. If The Matrix had been left as a standalone product, it would be one of the top 100 films of all time. Because it will forever be burdened with unnecessary and poorly made sequels, it is not.