Transport in London is overrated.
Whether it be due to lack of investment from central govt, or inaction/poor management from TfL, I've always gotten a fairly poor impression when I've had to travel within London's zones and deal with TfL's ticketing. Yes, it's cheaper than what I pay in rural-nowhere, but....
The stations are dirty, the operation is designed to be patronising towards passengers (where else in the country does there need to be someone with a megaphone telling adults in excruciating detail how to board a train every day?!), the system integrates poorly with the rest of the National Rail network (and this interoperability isn't prioritised as much as it should be, it's only getting worse), it's too hot on the vast majority of lines, some of the stock is ancient, crumbling to pieces and vandalised - and I genuinely don't see much in the way of innovation nowadays. Oyster feels like it's stood still for a number of years; I still have to fill in an unintuitive, lengthy form or wait on hold for ages to get a refund. I still have to find a member of staff in person every time I renew my Railcard, or else I miss out on the discount I am entitled to. I can still "not collect a top-up quickly enough". Passenger information provisions are poor, especially during disruption ("severe delays"!)
They've delivered on some really important infrastructure projects, like Crossrail - albeit not quite on time - and I only really have minor gripes in relation to the Elizabeth Line. I also can't claim they don't transport millions of passengers every day, but c'mon - it could be so much better for a capital city.