I really liked AotC when it came out, and still view it fondly.

I think the issue tends to be that TPM didn't hook as many people into the PT as was expected.

With TPM... so much was jam-packed into it, and it had such a different feel from the OT, that a lot of people had to see it two or three times just to wrap their heads around it. A lot of reviews these days contain "I saw The Phantom Menace like 5 times in theaters". I don't think that was the case with AotC. Some people didn't like TPM, and didn't come back. Some people came back hoping AotC was better, and decided it wasn't. Most people saw it once, shrugged their shoulders, and waited for RotS to figure out where the hell this was all heading. A small minority loved the film and followed the SW trend of multiple viewings.

Generally though, it succeeded because it was a Star Wars movie.