I took the boat from Siem Reap to Battambang. I have read iffy reviews of the trip but I loved it. It was 6--7 hours on wooden bench seating but I got a great view of the villages so I can easily forgive some discomfort. Many people actually sat on top of the boat but I wanted to stay out of the sun.
The lake was inexplicably rough the day I crossed but the ride was fine once we got on the river. Be advised that you go barreling through bushes and vegetation and can get scratched if you don't duck or put up the side canvas. Still, the views are fantastic. All the children in the villages wave madly and shout helloooooo. People come out to the moving boat on small flat boats propelled by someone kneeling kneeling and paddeling madly. They then literally jump onto the boat. It's quite the experience.
I stayed at the Seng Hout Hotel; check out the reviews on this website. I really liked the tuk tuk drivers that this hotel uses. I hired Tom (Tom_Touradventure@yhoo.com) who spent 9 straight hours driving me throughout the countryside for 15 dollars. His English is very good, he used to do translating for the Australian embassy, and he was extremely thoughtful. We went out to the killing cave, several temples, some as old as Angkor Wat, a vineyard, a village with bat trees, and the bamboo train, an experience not to be missed. He stopped at French colonial places for me to take pictures and would have done more if I hadn't been exhausted after 9 hours!
Everyone I met in Battambang, including tuk tuk driver david, email@example.com, was extremely kind and helpful. I really ended up liking the place even though it is definitely not for the feint of heart. The garbage piles are high, there are no traffic lights or stop signs, I saw an enormous rat, yet I thoroughly enjoyed it.
My best meal was at a new restaurant whose name escapes me but I believe I found it somewhere on this forum. It's owned by an Austraiian chef and his Cambodian partner. I had the national dish, Amok, which is fished steamed in banana leaves and here served beautifully in a fresh coconut. I paid 3 dollars for it and the restaurant has nice atmosphere too. Battambang is definitely worth a stop if you're traveling between Siem Reap and Phenom Penh.
I headed next to Phenom Penh which I got to by bus which was a good way to travel in a country with no apparent road rules.