Their "$6 burgers" are good, for fast food I would call them very good. Their breakfast options are also much better than their fast food competition.

I'm not a huge fan of fast food but consider Carl's Jr to be in the same league as In N Out which would be my favorite fast food guilty pleasure.

My experience has been that Carl's Jr, like In N Out doesn't prepare their stuff in advance, so they aren't as quick as other fast food places, but the food is superior. It's not healthy, but is tasty.