Hotel just about 3 star, a pity because the staff try to help.
The Opal is a three star hotel so we did not expect too much from it. It was ok - but only just.
The hotel frontage is tired and plain, but the lobby is very pretty with nice welcoming decoration throughout. We arrived to find the outer door was secured against entry and we had to be let in by the receptionist - common in San Francisco from what we saw. We were welcomed to the hotel and checked in, a little brusquely but efficiently. We were told of the local area attractions and given a detailed map - nice, and then given our room.  We were on the 5th floor and had to use the slow but steady lift to get there.
The room was clean and functional, a reasonable sized bed and plenty of storage. The bed was a little uncomfortable, but after a few nights we got use to it. The bathroom was small but acceptable with a basic bath/ shower. We found the shower was far too sensitive - even a slight touch of the tap made the water stone cold or boiling hot, something of concern if you had kids using it.
The fittings in the room were a little old, but fine to use and they suited the room well. Lighting was good, unlike many rooms I have stayed in. The tv was an older CRT type screen, it worked well but it is a little old fashioned compared to many other hotels.
The main  window looked out on a the building next door so the view was not that good, and without a bathroom fan you had to open the bathroom window to clear the steam from the shower.
The main door to the room was very poorly fitting which caused two problems, it allowed every noise from the corridor into the room and worse the light from the corridor illuminated the room at night. We left a suggestion that simple  maintenance would improve this, but we doubt it will happen. 
The air con had a mind all of itself, hot then cold. We never could get it to be consistent and assumed that some in built programme reset any changes we made. At least on "low" it was quiet.
 We had a package which included free wifi and breakfast. The wifi was good and worked well in the room and I found it more than adequate speed - there was the offer of a faster connection for $2 per night but I never used it. Breakfast was a nice continental style buffet - boiled eggs, toast, fresh fruit, yoghurts, orange or apple juice, coffee, tea and cakes. Not a bad start to the day.
Next door via a connecting door is mel's diner, we used it a fair bit and had several nice meals there. The fact it was so close and was linked to the hotel was a boon. Prices were a little up on what we expected but still ok.
The hotel is near several bus stops and within walking distance of a few shops, but the ever present "down and outs" on the local streets make the whole area feel run down and unwelcoming - a real pity.
We took a taxi from the airport to the hotel ( $55) on arrival but the receptionist booked a shuttle for our return saving us about $25 on the taxi. Check out at 4:30am was efficient, friendly and no problem.
 As a three star hotel the Opal just about makes it. Some nice touches like the breakfast, wifi and welcoming lobby are balanced by old fittings, a tired feel and maintenance issues. 
 I have to admit that we won't use it again, simply because we don't intend to go back to San Fransisco again, but that's not the fault of the Opal.  I feel the staff do try, but it is a microcosm of the city it is situated in - the Opal,  like San Francisco, really needs a boost to get it out of a state of slow decay.