The rooftop of Le Moon offers an awesome view of the Tonle Sap River (not better than FCC PP though). But the view of Wat Ounamloum is magnificent! The service is also highly commendable!
There is only one reason: the roof top & the view. service team very unfriendly, not caring, quite expensive, drinks poor and standard junk food. Just go there for the view.
The rooftop bar gets busy by 7pm or so, so get there early if you want the best seats! Tip around 2000 Riel, or more if you think service is exceptional.