This was a very good museum. It is focused only on the history of Angkor and its artifacts so you won't find random irrelevant exhibits to waste your time. This would be a good stating point before you visit the temples as it is very educational, but like every one else, I hit the temples first And this was last on my list.
That said, I do think the price of 12 per person to be high and I think that the no photos policy is really stupid. Museums normally restrict photos based on copyright, But none of this is copy written. All of this is easily photographed at the temples, but not allowed in the building for the same items. You must also leave purses, Backpacks and bags at the desk in open unlocked bins. While we didn't have any theft, It does make you worry the hole time you are looking at the exhibits if you will have anything stolen. Lastly, This museum gift shop make all others look like bargains. Extremely high prices on average gift shop items. Lots of items for over 2000 us dollars.
Like it said, I am glad I went, But a few simple policy changes would make this a great museum.