Great!
I recently stayed here two nights for business on a discounted rate. The hotel is lovely, if not a bit quirky. I would definitely stay here again, though, because overall, it's a great place! 
Check-in was fine. The staff were friendly and efficient. The lobby area is quite small and old-fashioned, similar to many that I've visited in Europe. It's nothing special, but I don't book hotels for the lobby. I saw that they had morning coffee service set out, which was a nice touch for East Coasters like me who get up early, but they were putting it away at 7 a.m. when I left for my meetings, and my guess is that it's only there as a courtesy until the restaurant opens for breakfast. The elevators are tiny and old as well, and I had the misfortune to be stuck in one for a few minutes the first day of my stay. That was a bit nerve-rattling, but fortunately that didn't happen again. An apology would have been nice, but I got the feeling this happens quite a bit, so maybe they don't even think to apologize after awhile. It certainly didn't ruin my stay, though.
The hallways are dingy; there's no denying that. I have to admit that when I was walking down the hall, I had in the back of my mind that I could always check out immediately and go to the Ritz if the room was as dreadful as the hall! Also, my room was in a strange location that shared a foyer with another room. I could hear that party quite well through my walls, which made sleep a bit difficult, since they clearly were on a West Coast schedule, and I was going to bed at 9. However, the room itself was wonderful! I had an amazingly comfortable bed, a desk and chair, which made working easy, and two stylish armchairs in front of a flat screen tv. The bathroom was all marble and lovely. 
I ordered room service for breakfast and both dinners, and the food was outstanding! My favorite was the chicken cooked under a brick. That was just delicious! I have heard that the hotel's restaurant is a destination of itself, and the food definitely proves why that is. 
The biggest downside, aside from the dingy halls and elevator fiasco, was that the wireless service was not good at all. It took me about 10 tries to get connected the first evening, and I gave up after the 10th try on my second evening. I had been working all day anyway and had a 6 a.m. flight out, so fortunately it didn't matter that much, but if you do depend on working in your room, you will want to bring a MiFi device or just plan on packing your patience and a little luck for the hotel wifi!
But, if you're coming to San Francisco purely on a leisure trip, I would recommend this place in a heartbeat! It's in a great location within walking distance of a couple of landmarks (including the Top of the Mark lounge), and the cable car goes right by the hotel.