One additional comment on the VOA process at Siem Reap: Kudos to their immigration staff for actually smiling and being pleasant, and the guy who hands your passport back was even joking around with several passengers.

Add me to the set of people who say that getting the VOA is no big deal (not much of a wait) at Siem Reap (arrived from Hong Kong). Especially after we were scared off the offical Cambodian e-visa website by malware warnings.