There is no question that the FCC has one of the best locations in town and as a result it is often full.
However, the rooms are getting very tired indeed. During my last stay I was pretty unimpressed by the dirty bathrooms and the constant mosquitos!
The restaurant is good even if a bit formulaic!

We stayed at "Palace View" room, an annex. Nice view from the room, and it was a perfect place to be in Phnom Penh for new year's eve.
We enjoyed seeing fire works from the roof terrace.
There was a security guard on the street only for the room at night time.
Nice breakfast served at FCC bar as well. (You can have it in the room as well.)

However, a few unpleasant things happened during our stay.
1. Our iphone, which we accidentally left in the room, was stolen!!
House keepers and receptionist said "We cannot find it" and that was it.

2. The room smelled like sewer water...
House keeper burns incense everyday in the evening, so its get better for a while.
But the smell continuously comes out from pipes in the bathroom...

Except these 2 events, we were happy about their service.
The bar FCC is worth visiting.

Stayed here for three night during July 2011. Room was good but waaay over priced. Staff were no where to be seen. I like when you know the staff are there if something goes missing or there's an emergency.
Upstairs is the bar area. Drinks are cheap. We checked out and headed up to ankgor for a couple of days to do the temples. We intended to return 2 days later but they refused to book us in. I forgot 50 dollars in the room and when I ran back up the cleaning lady said she never saw it. As Cambodia is developing there are more and more mOdern hotels available and surprisingly all with free wifi. We returned from ankgor which was amazing and stayed in the modern blue lizard hotel. Pm me if anyone needs any other tips.

We went here for dinner and it was great food with an extensive menu- loads of choice. Excellent view over the water and indoor/outdoor feel. A nice stop in Phnom Penh.
We also stopped for lunch in the cafe downstairs which is also owned by them, and that was good too with free wi-fi and good coffee!