In short
You come for Angkor, you stay for the town. Siem Reap is small, flat, bordered by a river, with a real café scene and a settled expatriate community.
The archaeological site is visited over several days, by bicycle or tuk-tuk.
What it really costs
One of the lowest costs of living in the region. A house with a garden costs what a room costs in Bangkok.
The Angkor pass is the real line of expenditure: several tens of euros, and the three-day pass is better value than the one-day.
When to go
November to February, dry and bearable. March to May is scorching, with temperatures that make the temples hard after ten in the morning.
The rainy season fills the moats and makes the site more photogenic, but the downpours are heavy.
What nobody tells you
You pay in US dollars almost everywhere, and the local currency serves only as small change.
Medical care is limited: for anything serious, evacuation is to Bangkok. This is the country in the region where insurance with repatriation genuinely counts.