We have only used it a few times so far since the weather has been on the cooler side.  That being said, I find that it is working well and is quiet enough.  We have it a relatively small room so we can run it on low to medium speed, which keeps it a little quieter.  I intentionally got a higher BTU to cool more area in our upstairs, not just the bedroom.  I like the features that it comes with as well.  I would have given it 4.5 if that was an option.  Also I can't comment ondurability, since we have only had it for a month.