Avoid unless you want to wait for days
The food at Phnom Penh is decent, but certainly not worth the terrible service and dentist's waiting room atmosphere that you have to deal with it to get your food. Uniformly, the waitstaff and owners are terrible at taking orders, delivering food in a timely manner, even taking money. If you want to go for a quick lunch, forget about it, it won't happen.
I've been there twice, to give them a chance, but I definitely won't be returning after this second time.