I stayed in Lopez for a week. It is located in an area of Kampala which used to be my home for a couple of years - and that is how I still feel when I am there.
There is big difference between the rooms - so try to get the ones facing the road. They are all around 30.000 Ugx (15 $). It seems to be the budget level in Kampala unless you want to stay places where they rent out per hour during the night. Kibuli Road where Lopez is located is just off Kabalagala night life - which runs 24 hours. If you want a quiet place and a good nights sleep then you might consider going up towards Muyenga.
Contact: +256 312 298758 or +256 772 392036