Are 3rd class train tickets okay in Sri Lanka?

Yes, 3rd-class train tickets are totally okay for travellers who want a bit of risk, plus a tight budget, and really that local feel, even if you give up reliable seating, personal space, and air conditioning, yes.

In practice, 3rd-class carriages usually have basic bench seating, and they depend on open windows and ceiling fans to cool things down. The main issue is overcrowding. For example, on busy lines such as Kandy to Ella, you might be standing for hours, and you will not really have a say in it. Still, it can be a lively, unfiltered window into Sri Lankan everyday life, with lots of chances to talk with locals. If you are going at peak commuter times or during public holidays, then it is smarter to move up to the reserved 2nd-class. For quick hops during quieter times, 3rd-class becomes a low-cost, culturally rich choice.