The problem with (and tragedy of) the Tube is that it could be so much better.
And, since I have seen what some other countries offered in their underground systems, I have found it somewhat claustrophobic - I don't like the design; or, rather, I prefer the continental versions (which are more spacious).
Granted, I had loved it (marvel of engineering, revolutionary form of transport, speedy means of transporting large numbers of humans, etc) until I saw what Paris, St Petersburg, Moscow, Prague, Brussels, and yes, even places such as Tashkent (the underground there is astonishing and wholly unexpected) offered in their respective underground systems which are genuine revelations.
Now, I wonder why London cannot be better.