UCL is a mixed bag. The lecturer’s quality varies. The emphasis at UCL is on research, so you can have a lecturer who just wants to get back to their research.
The fact that UCL draws students from all over the world is one of its main strengths, and you can find people from all over the world at UCL.
Having said all of that, I am really proud to be a student at UCL and wouldn’t change it for the world.