Three trips to Thailand, 2 stints in hospital, one with food poisoning, the other dehydration. Insured on both occasions and treated like Royalty in hospitals that are like 5* hotels. I wouldn't travel anywhere without it, but make sure that you disclose all pre-existing conditions, they will do anything to get out of paying.
And make sure if you can that you or the hospital contact your insurers as soon as you are admitted to hospital to make them aware.