I spent over three years studying at the Institute of English Studies of the University of Warsaw. The experience was wonderful. The faculty is qualified and competent with a good mastery of their subjects. The campus is in the middle of the city, hence very accessible.
The only downside would be with finding rooms in the student dormitories which is not easy. You may end up in a dormitory that you do not like.
Besides that, everything else is great at the University of Warsaw. Integration into the labor market is another major plus. There are plenty of jobs available. And once you graduate from a Polish higher education institution, you are eligible for the work permit.
I would definitely recommend the University of Warsaw.