People that go to UCL tend to be friendly and open and its a great mix of cultures and ethnicities. Unfortunately the university is extremely liberal and so if you are anything else than that expect judgement and criticism.
Moreover, the way UCL is run and managed is laughable at best. Old facilities, very disorganised Student Union and mediocre Support Services.
But as I said its a great place to meet and make friends for life and the University is high in rankings which helps when getting a job.