Nice inside, dodge the dodgy outside.
We stayed here for a couple of nights in late-May. 
Pretty much everything in the Renior was great - the staff were fantastic, it was clean and our room was really nice. It's a very pretty building (historical) and we always felt safe inside.
Unfortunately the mission is a block or so up the road which means it is a less than ideal location. 
If you're traveling on business or as a couple then there is absolutely nothing wrong with the Renior - it's right next to a muni stop which will get you downtown or down to Fisherman's Wharf.
However, I wouldn't recommend this as a place to bring your family - some of the sights in the immediate area aren't too pretty.
In saying this, the area is really on the way up - some restaurants and bars have recently opened up nearby and that's where I found the best coffee of my San Fran trip!