Yes, my friend always uses it in China. Make sure you select the correct roaming partner, this is very important.

Oops. I thought you were referring to Roam Like Home package.
For Roam Like Home, if your package doesn't come with that for free, you will need to subscribe for it first at Digi Centre.
You can check if your international roaming is activated using MyDigi app, check under Settings.

good to use roam like home for regular travel or one off package like roam 5, 15 or RM25 for 72 hour for 2GB +30minutes.

only watch out is NOT to overuse the data limit, otherwise charge per use or upto RM36 max per day.