Overall, this was a great experience. The room was tiny and very dorm-like, but clean and cozy. The shower kind of sucks, fairly low water pressure, but it did the job. The elevator was working, so I didn't end up having to climb up stairs to the 7th floor like the listing says. The attached coffee shop and restaurant have great food and drink for fairly good prices (and a 10% discount for staying in the hotel). Fantastic location, with Union Square and lots of amazing restaurants nearby. Watch out for "Tenderloin" neighborhood just to the west though. I didn't know about it before my trip and made the mistake of wandering in there one night. Definitely best avoided.
I did have an unfortunate check-in mishap, though. I had previously told the host that I would be arriving at 3 a.m. due to an extremely delayed flight and she had told me it was fine as they always have someone manning the desk. However, when I arrived at 3 a.m. on the dot, there was no one at the front desk so I was locked out, tired as hell and quite ticked off. Fortunately, the guy manning the Holiday Inn Express desk across the road let me hang out there for a bit. When the front desk guy for the Bartlett showed up almost an hour later, he was quite apologetic. He had apparently left a sign in the window, but it was damn near impossible to see as it had black text on a dark gray background in the dimly-lit entryway. The Holiday Inn guy hadn't noticed it either.
So, yeah, that sucked, but was probably a one-off incident. Other than that, this is a great pick for your stay in San Fran as long as you don't mind the no-frills dorm feel.