I go to SF a few times each year, and I prefer to walk the City rather than drive short distances. I have never felt unsafe walking around. Sure, there are many homeless there, but they are now in every large city for which I have visited recently. They mostly keep to themselves, with an occasional exception here and there but, again, not any worse that we have experienced elsewhere. The City has wonderful sites and excellent food and I would not advise any one to write it off outright.
I stayed at the Pulse once when it was relatively new for a one night stay before a cruise. I liked the urban vibe - thought they did a nice job on the decor. Everything was clean and immaculate, which, other than location and roominess, is one of my most important criteria. It is, as others have stated, more like a well-located hotel room. I do recommend a courtyard view as the street noise can be loud, especially with trash trucks coming early in the morning.
When I stay in SF (which is usually only for a few days), I do prefer to stay at the Ritz Residences for many reasons, one of which is that parking is included there, which is a huge benefit if you're going to have a car, which I mostly always do as we drive up from SoCal. However, the Pulse is relatively available to trade into via II, so if you are looking for a week long stay, it may be a very cost-effective option. If you can go without a car, Uber of Lyft is a great option.