The only real issue with S-turns is that you want to be done with them with enough time left to re-establish a good straight approach. How long you need to do that depends on the aircraft - larger aircraft need more time. If I think the tower is requesting S-turns too late, I'll just opt for a go-around.
But flying them is no big deal. Turn to the left, turn to the right, etc. You might have to turn the autopilot off if you were doing a coupled approach, but you'd only be doing S-turns in VMC anyway, so that's not a big deal unless you need the coupled approach for legal reasons.
7 billion, one nation, imagination...it's a beautiful day