Ideal location but extremely loud!
We are a couple in our early 30's that booked through Hotwire on a friend's recommendation and Hotel Fusion is what we got. After booking, we read reviews and instantly regretted using Hotwire but we didn't have a choice so we rolled with it and hoped for the best. 
We stayed at Fusion Jan 10, 11 & 12. This was our first trip to SF and this was also our 10 year anniversary. We had let the hotel know ahead of time that we'd prefer a 4th or 5th floor room (based on reviews) and that we'd be arriving late (11pm-ish). We were assured our request would be honoured. Upon arrival, we were told our room on the 4th floor was given away (despite the room was already paid in full a month in advance) so we were given a room on the 3rd floor with a room with a king size bed and plenty of room, which was nice. But seeing as the room was on the 3rd floor, overlooked Ellis Street and the nightclub below, we were subjected to being woken up 3-5 times a night because of street noise from the nightclub - and we were there mid-week (Tues, Wed, Thurs)!!! We are really easy going but when you just want to sleep due to a busy day of sight-seeing and jet jag, the noise was excessive and we were relieved we only booked this hotel 3 nights. I can't imagine staying there on a Fri & Sat. 
The positives are that it's an ideal location for shopping, public transportation, restaurants, landmarks, etc. The room was clean and a decent size. There is a continental breakfast that is just okay so we didn't bother. I did see instant oatmeal, oranges, apples, lots of pastries and coffee/tea/orange juice/apple juice.
We didn't use the fitness centre but there really isn't much in there.
I wouldn't recommend this hotel to couples, families or for business - it's just too loud. Possibly a student break crowd?
We loved SF but would look somewhere else to stay.