Pricey, dark rooms, few amenities in tourist central. Not a 4* hotel.
Pros: Great breakfast restaurant on site, good tourist location, tall and comfy beds
Cons: Expensive, darkest hotel room I've ever stayed in, bar closes *really* early, basic over-bath shower, thin walls make for noise both above and to the sides, $13/day internet charge, poor view, no pool
I'll preface this review by saying that the Argonaut isn't a bad hotel, in that it's a comfortable bed to sleep in that's well located in San Francisco's tourist land. But for a four star property there are plenty of shortcomings, so this low score reflects how it delivered on expectations.
The room's thin walls mean you'll hear what's going on upstairs and with your neighbours on both sides. Running water through the pipes is noisy enough to wake you and the mini bar fridge kicks up like a lightsabre at random times too. 
The room is dark too - the dimmest hotel room that I've ever stayed in. The window shutters won't stay open on their own to let light in, but they also won't shut for complete darkness at night. It's like permanent twilight, which isn't ideal for jetlag or enjoying the room. 
The view out from my room faced into the hotel, across to other rooms. Didn't help with the low light situation and was uninspiring when working in the room. 
Wi-Fi/Internet has a $13 charge per day and is the worst connection speed of paid Wi-Fi I've ever experienced.
While the associated breakfast restaurant did good eggs and OJ, the attached wine bar shut absurdly early. We wouldn't be served even just after 9pm.
All that would be acceptable in a more budget property, but in mid-October the $300-349 Friday night charge is a lot. 
The location is great for access, the exterior of the building looks great, and I had a fantastic time exploring San Francisco using this hotel as a base. But as a frequent traveller this place just doesn't match up to expectation, hence the low score.