DH went. Left home at about 3 am, drove the the outskirts of London, got a train and joined the queue around 6 am. Got into Westminster Hall around 5 pm, and was lucky enough to be at the front when they did the 'changing of the guards', so saw that ceremony, before he was able to bow to HM and move through.
He called me when he left and said he'd found the whole thing quite emotional. The atmosphere in Westminster Hall was extremely powerful. He'd thanked one of the police officers who guided him, who said it was his honour to be there for the Queen.
He was lucky to be with some lovely people in the queue, one couple were telling him all about their visit to Brazil, where we are planning to go in 2023, as well as the inevitable talk about the Royal Family. He said that people in the queue were extremely impressed with both Anne and Sophie, and how supportive they'd been towards the new King.
The Tate and Globe and other places along the way had their facilities available, so as long as you had a wristband, you were fine. The queue moved pretty quickly until the last mile.
We are royalists, DH was keen to go to pay his respects, he's fit, healthy, newly retired and didn't spend our food money on fuel!!! (Some of the assumptions thrown about on this thread are crazy). He is also ex-forces, so the Queen was his boss. I would have gone, but have surgery on Wednesday and don't want to risk picking up Covid or any other bug at the moment.
He is very happy that he 'bothered'.