Our experiences of Siem Reep can be split into two: the temples and Cambodia itself.
The temples of Angkor were truly stunning. Just look at the pictures.
The central temples around Angkor Wat were quite crowded with tourists but quieter than usual thanks to the chaos at Bangkok airport. It was a surprising just how many westerners there were - especially Americans. Angkor Wat itself never felt crowded as it was so big. Really worth getting up early or visiting around sunset to experience the temples in peace. Everywhere was easy to walk around and you had to stop yourself from taking too many photos due to the vast number of sublime views.
We got a 3 day ticket to visit the temples. We hired a taxi driver and a guide for the first day to take us around the central temples and learn about the history, architecture and religious meanings. The second day we just kept the driver and visited the outer temples, which were much more peaceful. Banteay Srei was especially beautiful. We also saw a waterfall and river carvings to the north (hard long walk, not worth the effort) and a landmine museum. By the end of the second day we were templed out. So on the third day we just returned to Angkor Wat for the sunset.
Cambodia itself was eye-opening.The Cambodians smiled a lot and were mostly friendly, a welcome change from Kuala Lumpur. However, the smiles and hospitality didn't seem as genuine as those in Thailand. The people were very poor and still recovering from the Khmer Rouge regime (they killed 1/5 of the population and landmines still litter the country). Begging and selling was very aggressive. Being approached by landmine victims and poor children hungry for your dollars was very moving. Although we were shocked at how quickly we hardened to all the attention and just wanted to be left alone to walk unhindered. We felt like we were seen as walking ATM machines.
On our last day we visited the massive Tongle Sap lake. We were the only passengers on a long motor boat, which we had to fight past a photographer to board. The journey out through the floating villages of Vietnamese was impressive. Once we got past the villages and vegetation into open water the trip quickly went downhill. The driver tried to explain to us that we would now be going to visit a crocodile farm and buys books for school children. The "school" turned out to be a floating "classroom" full of children each clutching notes which had been given to them by tourists. Other tourists had bought exercise books from a floating book shop to give to the pupils, hopefully not part of another tourist-fleecing project. We made a donation into their text book fund, took a photo and left. Many other tourists had the same miffed look on their faces as us. We tried to tell our driver that we didn't want to visit the crocodile farm but he took us anyway. Turned out to be a floating restaurant/giftshop with a couple of small open cages packed full of very unhappy crocs. Upon leaving the boat the driver had the nerve to ask for a tip (on top of the fare that we had already paid which was equal to a teacher's monthly salary). As we walked to the taxi we ignored a lady trying to sell us plates. It was only once we were in the taxi that we noticed that the plates had photos of our faces printed on them!
It was wonderful to visit the amazing temples, enjoy the delicious food and visit the markets of Siem Reap but 5 days was more than enough and we were glad to return to KL and be ignored by everyone for a few days.