I love this place! I call it my "Seattle home" as I visit Seattle several times a year and I don't feel right unless I'm staying here. From the cheapest rooms, where you have to share a shower down the hall, to the fanciest rooms that make you feel like a freaking rockstar -- Ace is the best! Their beds are the most comfortable beds I've ever slept in, their decor is just awesome, and the rooms are very minimalist but with everything a weary traveler could need.
The only negative: it's REALLY loud on Fridays and Saturdays -- there's a bar that plays loud music directly under the most affordable rooms, and there are a lot of drunken "whoohoo-ers" wandering beneath your window at night. To this day, the worst fight I've seen in my LIFE has taken place right outside the window to our room. BUT! That is to say, that's not the hotel's fault, just know that it's a lively neighborhood come night time.
The upside of the neighborhood is that EVERYTHING is within walking distance. Bars, restaurants, hair salons, etc. I wish I could live at the Ace Hotel in Belltown.