Entering Sri Lanka is efficient and nearly all international service is through Colombo (CMB). Check if you need a visa, but if you do (as is most likely), an Electronic Travel Authorisation (ETA) can be obtained online (https://www.eta.gov.lk).
This isn’t a large airport and arriving on a mid-week late evening (February 2017) there was a pretty good (under 10 minute) wait at passport control.
There is an arrivals duty free and a large number of mostly similar household appliance stores, suggesting that these items are heavily taxed and intended for local returners who need a new microwave.
Post-customs in the secure arrivals area you’ll find multiple bank foreign exchange booths – my guidebook also reports ATMs although I didn’t see them. As with Indian and Turkish airports, entrance to the terminal building is for passengers only so any touts (and in fact there are few at CMB) are kept on the curbside. Once at the arrivals curbside there is a booth (against the terminal wall) that will order cabs for you in addition to the lineup. Kangaroo Cabs are reliable and uber is operating in Sri Lanka. Cab fare into town (including toll) was about SR2,400- for my journey.
You can purchase smartphone SIM cards in the arrivals area – the main providers are Mobitel and Dialog, and they and others offer “tourist packages” – or you can find an in town location later. I purchased mine at the Mobitel store in the downtown World Trade Center, where I got a monthly SIM card with 8GB of data for $6.64. Either way Sri Lanka has affordable and excellent cell coverage.
The airport is about 30km north of town and served by a tolled highway – if your driver asks if he should take the highway, say yes as it is much faster.
The airport runway is under daily rehab through April 2017 which has increased check in times.