The first one I tried wasn't as bad because they didn't put half the shit on it. It was opening day and they half-assed everything because it was busy and it ended up being mainly burger, cheese, and meat. I really like fried onions on burgers and wanted to actually taste the sauce, so I gave it another chance. Like you said, it was sloppy as hell and just doesn't mesh well. One minute I tasted mainly onions, then overpowering cheese and sauce, then a little seasoned beef. And that sauce with cheddar....
Most of these places may design a solid burger in small testing places with strong controls over every factor of the process. When it rolls out and 70 IQ subhumans are making it with oversight by the local 40 year old losers at life, it needs to be a really good concept to pass that threshold. For me, it just didn't do it. I couldn't taste the fried onions, and the cheddar and sauce did not taste good together. I had a Big Mac yesterday just to complete the picture. Far superior. And as Moon said, the double Big Mac is even better. McDonalds hasn't designed a solid burger concept since the 70s.