We have that kind of place in Luxembourg. It's near the train station where you would find all the related issues : prostitution, dealers, organized crime, homeless people ...
There are some rules you have to respect : no dealing on the grounds, no violence, no police presence as long as there's no emergency.
The one thing about it is that there's clean equipment to inject (to avoid spreading of diseases), trained personnel in case of overdose, social workers, counseling programs (and they are quite successful), medical facilities (to help with all kind of problems, from testing to cleaning up wounds).
So I think these safe consumption houses are only as positive as there are programs helping the consumers.

I'm just glad peoples attitudes are adjusting to reality, at least at the local level.