If you need a breather from roaming the streets of Siem Reap, haggling with feisty street vendors, etc… then be sure to visit Upstairs Cafe. We stopped in for coffee and cake, both of which were excellent. My friend loved her cinnamon latte which was made with syrup that is made in-house and from scratch. The chocolate fondant was rich, chocolate-y and exactly what I needed to fuel my second wind. They also have a great selection of TWG teas. The interior is cozy with a bit of an eclectic arts-and-craftsy decor and it feels very "homey," so beware… you may stay longer than intended. We easily killed an hour sipping our drinks, flipping through books and magazines, and doing a whole lot of nothing. We also got a chance to meet the owner who is originally from France, very lovely and very easy to chat to.
Upstairs Cafe is a bit off the beaten track, but within easy walking distance of pretty much anything in the town centre. We loved it.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.