The location of this unit is unparalleled, and made for an excellent weekend in Santa Monica. That said, I would consider this unit to be more of a hostel than a typical AirBnB. I say this because the owner manages multiple units in the same building - and it was clear by the furnishings, linens, etc. that the unit is not lived in.
The biggest downside is that our room wasn't cleaned and ready for us until 4.5 hours after the stated check in time. Not a huge deal for us, as we left our stuff and hit the beach - but it was kind of gross to see the previous renters mess.
Once cleaned, the place worked out well. Beds were comfortable. Furniture was a bit run down but served its purpose. Maid staff was very friendly. (Maid staff is another reason it felt more like a hostel.)
Overall, I would recommend staying here - just make sure your expecting a hostel-like experience.